Build reliablity fixes

[kgyrtkirk]

• disable parallel builds in CI - could potentially fix the shader issue by making the build more reliable
• possibly enable m2 artifact restoration for integration test builds
• enable batch mode -B (disables download progress)
• fix one test missing NullHandling.init

[abhishekagarwal87]

Thanks for taking this up. How much slowdown did you observe after disabling parallel build? I have seen dramatic difference locally when building parallelly vs sequentially.

[kgyrtkirk]

In CI builds - I don't see any significant differences; but they all used the ./it.sh ci which was executing a non-parallel build

I think this patch may only affect the execution time of locally run integraion-tests

For the command: time mvn verify -P integration-tests -pl integration-tests -Dgroups=http-endpoint1

	without patch	with patch
#1	2m22	2m49
#2	2m17	2m30
#3	2m8	2m30

[kgyrtkirk]

this patch also reduces the gap between seq/paralell build for a command like:
time mvn -q clean install -P dist -DskipTests -Pskip-static-checks

worktree is already built built; artifacts cached

	w/o; seq	w/o; T8	patch; seq	patch;T8
run#1	6m17	2m18	3m50	2m10
run#2	6m22	2m17	3m49	2m11
run#3	6m18	2m16	3m54	2m10