use InstrumentationConfig where possible

[zeitlinger]

Some places use system properties directly instead of the InstrumentationConfig, which is available with a static getter

This is unexpected when using the declarative config file.

Examples of wrong usage:

• opentelemetry-java-instrumentation/instrumentation-api/src/main/java/io/opentelemetry/instrumentation/api/internal/ContextPropagationDebug.java

  Line 35 in 57e957d

  boolean agentDebugEnabled = ConfigPropertiesUtil.getBoolean("otel.javaagent.debug", false);

  
  Examples of correct usage:

• opentelemetry-java-instrumentation/instrumentation/kotlinx-coroutines/kotlinx-coroutines-1.0/javaagent/src/main/java/io/opentelemetry/javaagent/instrumentation/kotlinxcoroutines/instrumentationannotations/WithSpanInstrumentation.java

  Line 60 in ca3c685

  AgentInstrumentationConfig.get().getBoolean("otel.javaagent.debug", false));

• opentelemetry-java-instrumentation/instrumentation-api-incubator/src/main/java/io/opentelemetry/instrumentation/api/incubator/config/internal/CommonConfig.java

  Line 40 in 5b287e3

  peerServiceResolver =

  (also available for spring starter)

Note: Double check that InstrumentationConfig is really initialized before.