Resolve deprecation warnings in RuntimeHintsAgentPlugin

[kwondh5217]

Motivation

• This PR aims to resolve the deprecation warnings in RuntimeHintsAgentPlugin.java.
  Currently, the Gradle build shows the following warning with -Xlint:deprecation:

build/hint/RuntimeHintsAgentPlugin.java:55: warning: [deprecation] <T>create(String,Class<T>,Action<? super T>) in TaskContainer has been deprecated
 Test agentTest = project.getTasks().create(RUNTIMEHINTS_TEST_TASK, Test.class, test -> {
                                    ^
  where T is a type-variable:
    T extends Task declared in method <T>create(String,Class<T>,Action<? super T>)

Modification

• Replaced project.getTasks().create(...) with project.getTasks().register(...) to avoid using the deprecated API.

Result

Closes gh-34389

[bclozel]

Thanks @kwondh5217 ! I've rebased your change on the 6.2.x branch and applied it.

[kwondh5217]

Thanks @bclozel !