Reject illegal placeholder in Maven CI friendly version property

[famod]

Results in a more useful error message than:

java.lang.IllegalArgumentException: named capturing group is missing trailing '}'

e.g. (from the test):

java.lang.IllegalArgumentException: Illegal placeholder in Maven CI friendly version property "revision": ${main.project.version}
	Please consult https://maven.apache.org/maven-ci-friendly.html#single-project-setup

Came up more than once, last time I noticed was here: https://quarkusio.zulipchat.com/#narrow/stream/187038-dev/topic/BootstrapMavenException.20when.20using.20.24.7Brevision.7D

[quarkus-bot]

Failing Jobs - Building fd40b5f

Status	Name	Step	Failures	Logs	Raw logs
✖	Gradle Tests - JDK 11 Windows	Build	⚠️ Check →	Logs	Raw logs

[famod]

@gsmet did you decide to not backport it in the end? Asking also because of #22171 which was just created.

[famod]

FTR, this PR also covers what has been reported in #22171 (No group with name {version}).

[gsmet]

It didn't look very critical to backport but yeah, we can do it.