RFR: 8318662: Refactor some jdk/java/net/httpclient/http2 tests to JUnit [v2]

[Mahendra Chhipa]

> Refactoring following httpclient/http2 testng test to JUnit :
> test/jdk/java/net/httpclient/http2/BadHeadersTest.java
> test/jdk/java/net/httpclient/http2/BadPushPromiseTest.java
> test/jdk/java/net/httpclient/http2/BasicTest.java
> test/jdk/java/net/httpclient/http2/ConnectionFlowControlTest.java
> test/jdk/java/net/httpclient/http2/ContinuationFrameTest.java

Mahendra Chhipa has updated the pull request incrementally with one additional commit since the last revision:

  Implemented the review comments.

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Changes:
  - all: https://git.openjdk.org/jdk/pull/27388/files
  - new: https://git.openjdk.org/jdk/pull/27388/files/055a1cfe..ea197296

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=27388&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=27388&range=00-01

  Stats: 74 lines in 5 files changed: 0 ins; 7 del; 67 mod
  Patch: https://git.openjdk.org/jdk/pull/27388.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27388/head:pull/27388

PR: https://git.openjdk.org/jdk/pull/27388