HADOOP-19891: update cloud connector testing requirements

[ajfabbri]

Description of PR

Now that we have some S3A integration testing in CI, update PR template and
hadoop-aws testing doc. The changes clarify that manual testing is still
required.

How was this patch tested?

Documentation only: viewed rendered markdown.

For code changes:

• Does the title or this PR starts with the corresponding JIRA issue id (e.g. 'HADOOP-17799. Your PR title ...')?
• [na] Object storage: have the integration tests been executed and the endpoint declared according to the connector-specific documentation?
• [na] If adding new dependencies to the code, are these dependencies licensed in a way that is compatible for inclusion under ASF 2.0?
• [na] If applicable, have you updated the LICENSE, LICENSE-binary, NOTICE-binary files?

AI Tooling

If an AI tool was used:

• [na] The PR includes the phrase "Contains content generated by "
  where is the name of the AI tool used.
• My use of AI contributions follows the ASF legal policy
  https://www.apache.org/legal/generative-tooling.html

[hadoop-yetus]

🎊 +1 overall

Vote	Subsystem	Runtime	Logfile	Comment
+0 🆗	reexec	18m 27s		Docker mode activated.
			_ Prechecks _
+1 💚	dupname	0m 0s		No case conflicting files found.
+0 🆗	codespell	0m 0s		codespell was not available.
+0 🆗	detsecrets	0m 0s		detect-secrets was not available.
+0 🆗	markdownlint	0m 0s		markdownlint was not available.
+1 💚	@author	0m 0s		The patch does not contain any @author tags.
			_ trunk Compile Tests _
+0 🆗	mvndep	2m 28s		Maven dependency ordering for branch
+1 💚	mvninstall	51m 56s		trunk passed
+1 💚	mvnsite	19m 58s		trunk passed
+1 💚	shadedclient	107m 56s		branch has no errors when building and testing our client artifacts.
			_ Patch Compile Tests _
+0 🆗	mvndep	0m 28s		Maven dependency ordering for patch
+1 💚	mvninstall	45m 59s		the patch passed
+1 💚	blanks	0m 0s		The patch has no blanks issues.
+1 💚	mvnsite	19m 48s		the patch passed
+1 💚	shadedclient	53m 46s		patch has no errors when building and testing our client artifacts.
			_ Other Tests _
+1 💚	asflicense	0m 47s		The patch does not generate ASF License warnings.
		229m 26s

Subsystem	Report/Notes
Docker	ClientAPI=1.54 ServerAPI=1.54 base: https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-8503/1/artifact/out/Dockerfile
GITHUB PR	#8503
Optional Tests	dupname asflicense mvnsite codespell detsecrets markdownlint
uname	Linux 9c130131b2d5 5.15.0-174-generic #184-Ubuntu SMP Fri Mar 13 18:41:50 UTC 2026 x86_64 x86_64 x86_64 GNU/Linux
Build tool	maven
Personality	dev-support/bin/hadoop.sh
git revision	trunk / a9977fa
Max. process+thread count	567 (vs. ulimit of 10000)
modules	C: hadoop-tools/hadoop-aws . U: .
Console output	https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-8503/1/console
versions	git=2.43.0 maven=3.9.15
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[ajfabbri]

CI failure will be addressed separately: HADOOP-19893