Get rid of applying Shadow plugin for itself

[Goooler]

Closes #965.

---

• CHANGELOG's "Unreleased" section has been updated, if applicable.

[Goooler]

dua .m2/repository/com/gradleup/shadow/shadow-gradle-plugin/8.3.1-SNAPSHOT/
   4.10 KB maven-metadata-local.xml
   4.10 KB shadow-gradle-plugin-8.3.1-SNAPSHOT-all.jar.asc
   4.10 KB shadow-gradle-plugin-8.3.1-SNAPSHOT-javadoc.jar.asc
   4.10 KB shadow-gradle-plugin-8.3.1-SNAPSHOT-sources.jar.asc
   4.10 KB shadow-gradle-plugin-8.3.1-SNAPSHOT.jar.asc
   4.10 KB shadow-gradle-plugin-8.3.1-SNAPSHOT.module.asc
   4.10 KB shadow-gradle-plugin-8.3.1-SNAPSHOT.pom
   4.10 KB shadow-gradle-plugin-8.3.1-SNAPSHOT.pom.asc
   8.19 KB shadow-gradle-plugin-8.3.1-SNAPSHOT.module
  65.54 KB shadow-gradle-plugin-8.3.1-SNAPSHOT-sources.jar
  90.11 KB shadow-gradle-plugin-8.3.1-SNAPSHOT-javadoc.jar
 368.64 KB shadow-gradle-plugin-8.3.1-SNAPSHOT.jar
   8.49 MB shadow-gradle-plugin-8.3.1-SNAPSHOT-all.jar
   9.06 MB total

dua .m2/repository/com/gradleup/shadow/shadow-gradle-plugin/8.3.2-SNAPSHOT/
   4.10 KB maven-metadata-local.xml
   4.10 KB shadow-gradle-plugin-8.3.2-SNAPSHOT-javadoc.jar.asc
   4.10 KB shadow-gradle-plugin-8.3.2-SNAPSHOT-sources.jar.asc
   4.10 KB shadow-gradle-plugin-8.3.2-SNAPSHOT.jar.asc
   4.10 KB shadow-gradle-plugin-8.3.2-SNAPSHOT.module.asc
   4.10 KB shadow-gradle-plugin-8.3.2-SNAPSHOT.pom
   4.10 KB shadow-gradle-plugin-8.3.2-SNAPSHOT.pom.asc
   8.19 KB shadow-gradle-plugin-8.3.2-SNAPSHOT.module
  65.54 KB shadow-gradle-plugin-8.3.2-SNAPSHOT-sources.jar
  90.11 KB shadow-gradle-plugin-8.3.2-SNAPSHOT-javadoc.jar
 368.64 KB shadow-gradle-plugin-8.3.2-SNAPSHOT.jar
 561.15 KB total

diff shadow-gradle-plugin-8.3.1-SNAPSHOT.pom shadow-gradle-plugin-8.3.2-SNAPSHOT.pom

12c12
<   <version>8.3.1-SNAPSHOT</version>
---
>   <version>8.3.2-SNAPSHOT</version>
97,103d96
<     <dependency>
<       <groupId>org.codehaus.groovy</groupId>
<       <artifactId>groovy-backports-compat23</artifactId>
<       <version>3.0.8</version>
<       <scope>compile</scope>
<       <optional>true</optional>
<     </dependency>

diffuse diff --jar shadow-gradle-plugin-8.3.1-SNAPSHOT.jar shadow-gradle-plugin-8.3.2-SNAPSHOT.jar

OLD: shadow-gradle-plugin-8.3.1-SNAPSHOT.jar
NEW: shadow-gradle-plugin-8.3.2-SNAPSHOT.jar

 JAR   │ old       │ new       │ diff
───────┼───────────┼───────────┼──────────
 class │ 737.7 KiB │ 740.3 KiB │ +2.5 KiB
 other │  10.6 KiB │  10.7 KiB │    +89 B
───────┼───────────┼───────────┼──────────
 total │ 748.3 KiB │ 750.9 KiB │ +2.6 KiB

 CLASSES │ old  │ new  │ diff
─────────┼──────┼──────┼────────────
 classes │  154 │  155 │ +1 (+1 -0)
 methods │ 1909 │ 1917 │ +8 (+8 -0)
  fields │  796 │  801 │ +5 (+5 -0)

=================
====   JAR   ====
=================

 size    │ diff     │ path
─────────┼──────────┼─────────────────────────────────────────────────────────────────────────────────
 2.4 KiB │ +2.4 KiB │ + com/github/jengelman/gradle/plugins/shadow/legacy/LegacyShadowPlugin.class
    89 B │    +89 B │ + META-INF/gradle-plugins/com.github.johnrengelman.shadow.properties
     0 B │      0 B │ + com/github/jengelman/gradle/plugins/shadow/legacy/
 3.7 KiB │   +122 B │ ∆ com/github/jengelman/gradle/plugins/shadow/ShadowPlugin$_apply_closure1.class
─────────┼──────────┼─────────────────────────────────────────────────────────────────────────────────
 6.2 KiB │ +2.6 KiB │ (total)


=====================
====   CLASSES   ====
=====================

CLASSES:

   old │ new │ diff
  ─────┼─────┼────────────
   154 │ 155 │ +1 (+1 -0)

  + com.github.jengelman.gradle.plugins.shadow.legacy.LegacyShadowPlugin


METHODS:

   old  │ new  │ diff
  ──────┼──────┼────────────
   1909 │ 1917 │ +8 (+8 -0)

  + com.github.jengelman.gradle.plugins.shadow.legacy.LegacyShadowPlugin $createCallSiteArray() → CallSiteArray
  + com.github.jengelman.gradle.plugins.shadow.legacy.LegacyShadowPlugin $getCallSiteArray() → CallSite[]
  + com.github.jengelman.gradle.plugins.shadow.legacy.LegacyShadowPlugin $getStaticMetaClass() → MetaClass
  + com.github.jengelman.gradle.plugins.shadow.legacy.LegacyShadowPlugin <init>()
  + com.github.jengelman.gradle.plugins.shadow.legacy.LegacyShadowPlugin apply(Object)
  + com.github.jengelman.gradle.plugins.shadow.legacy.LegacyShadowPlugin apply(Project)
  + com.github.jengelman.gradle.plugins.shadow.legacy.LegacyShadowPlugin getMetaClass() → MetaClass
  + com.github.jengelman.gradle.plugins.shadow.legacy.LegacyShadowPlugin setMetaClass(MetaClass)


FIELDS:

   old │ new │ diff
  ─────┼─────┼────────────
   796 │ 801 │ +5 (+5 -0)

  + com.github.jengelman.gradle.plugins.shadow.legacy.LegacyShadowPlugin $callSiteArray: SoftReference
  + com.github.jengelman.gradle.plugins.shadow.legacy.LegacyShadowPlugin $staticClassInfo: ClassInfo
  + com.github.jengelman.gradle.plugins.shadow.legacy.LegacyShadowPlugin $staticClassInfo$: ClassInfo
  + com.github.jengelman.gradle.plugins.shadow.legacy.LegacyShadowPlugin __$stMC: boolean
  + com.github.jengelman.gradle.plugins.shadow.legacy.LegacyShadowPlugin metaClass: MetaClass