PR build limitation: test framework takes the default extension repo branch instead of current change

[JasonFengJ9]

extended.openjdk PR build still shows the errors eclipse-openj9/openj9#16074 due to the test framework taking the default JDK19 extension repo instead of this PR.
Launched an internal grinder w/ this change and the three tests in question are skipped or passed.

Originally posted by @JasonFengJ9 in ibmruntimes/openj9-openjdk-jdk19#34 (comment)

FYI @llxia @AdamBrousseau

[llxia]

PR test build in the extension repo did not get triggered with your personal extension repo and branch (i.e., JasonFengJ9 and jvmitprops are expected):
https://openj9-jenkins.osuosl.org/job/Test_openjdk19_j9_extended.openjdk_aarch64_mac_Personal/1/

Openj9 pipeline should be updated to trigger test builds with corresponding JDK_REPO and JDK_BRANCH in PR builds.

[AdamBrousseau]

Opened infrastructure/issues/7363