Add more CORS regex tests and fix the CORS regex example

[sberyozkin]

Fixes #34718.

This PR adds few more tests using the regex documented in the docs.

Note, the same regex requires different treatment when using it directly from Java (\\. to represent a dot char) but \\\\. if the same regex is supplied from the properties.

I've proposed some text suggesting why it is the case, please tune it as required.
CC @gsmet @dmlloyd @radcortez and everyone else is welcome to comment :-)

[github-actions]

🙈 The PR is closed and the preview is expired.

[dmlloyd]

Maybe "if you use regular expressions in an application.properties file"?

[quarkus-bot]

Failing Jobs - Building 8d9a5b0

Status	Name	Step	Failures	Logs	Raw logs
✔️	JVM Tests - JDK 11
✖	JVM Tests - JDK 17	Build	Failures	Logs	Raw logs
✔️	JVM Tests - JDK 19

Full information is available in the Build summary check run.

Failures

⚙️ JVM Tests - JDK 17 #

- Failing: extensions/opentelemetry/deployment 
! Skipped: extensions/micrometer-registry-prometheus/deployment extensions/micrometer/deployment extensions/quartz/deployment and 32 more

📦 extensions/opentelemetry/deployment

✖ io.quarkus.opentelemetry.deployment.instrumentation.VertxOpenTelemetryTest. - More details - Source on GitHub

java.lang.RuntimeException: java.lang.RuntimeException: Failed to start quarkus
	at io.quarkus.test.QuarkusUnitTest.beforeAll(QuarkusUnitTest.java:705)
	at org.junit.jupiter.engine.descriptor.ClassBasedTestDescriptor.lambda$invokeBeforeAllCallbacks$12(ClassBasedTestDescriptor.java:395)

[sberyozkin]

Test failure is unrelated, this PR only adds another CORS regex test, and updates the docs