Revert "Fix help webapp compiling JSPs when run on Java 17+"

[akurtakov]

Reverts #20 as it breaks I-build with:

15:37:05  [ERROR] Failed to execute goal org.eclipse.tycho:tycho-compiler-plugin:3.0.0-SNAPSHOT:validate-classpath (default-validate-classpath) on project org.eclipse.help.webapp: Execution default-validate-classpath of goal org.eclipse.tycho:tycho-compiler-plugin:3.0.0-SNAPSHOT:validate-classpath failed: org.osgi.framework.BundleException: Bundle org.eclipse.help.webapp cannot be resolved:org.eclipse.help.webapp [36]
15:37:05  [ERROR]   Unresolved requirement: Import-Package: org.eclipse.jdt.core.compiler
15:37:05  [ERROR]     -> Export-Package: org.eclipse.jdt.core.compiler; bundle-symbolic-name="org.eclipse.jdt.core"; bundle-version="3.30.100.qualifier"; version="0.0.0"
15:37:05  [ERROR]        org.eclipse.jdt.core [37]
15:37:05  [ERROR]          Unresolved requirement: Require-Bundle: org.eclipse.core.resources; bundle-version="[3.17.0,4.0.0)"