Stop shading libraries

[felixbarny]

Some advantages

• Required for Add support for community supported plugins #937 so that elastic-apm-agent can be used in test module.
  This is currently not possible because Byte Buddy is shaded in elastic-apm-agent but external plugins would depend on the regular Byte Buddy as a compile dependency.
• Simplifies Dynamic logger ecs reconfig #1261
• Simplifies log4j2 error capturing instrumentation
• Easier source jar generation -> simplifies debugging the agent
• Simplifies or removes shading config

Depends on #1338
Prerequisite for #937