3.0 archetypes minor issues

[barchetta]

While testing the new 3.0 archetypes I ran into these issues:

• bare-se and bare-mp archetypes use endpoint /simple-greet and not /greet which is inconsistent with what is in the README. (PR created)
• database-se README mentions "/greet" endpoint, even though there is no such endpoint. (PR created)
• We should do some additional manual end-user testing of the six basic archetypes and carefully verify they work as expected and the READMEs are accurate.
  • [Readme] Native image
  • [Readme] Jlink
  • [Readme] Exercise the application section on all archetypes
• Fix Database SE hanging test for db != h2 (PR created)
• Fix media support with none selected (PR created)

These projects were generated using the legacy maven wrappers. For example

mvn archetype:generate -DinteractiveMode=false   \
  -DarchetypeGroupId=io.helidon.archetypes  \
  -DarchetypeArtifactId=helidon-database-mp   \
  -DarchetypeVersion=3.0.0-RC1   \
  -DgroupId=io.helidon.examples -DartifactId=helidon-database-mp   -Dpackage=io.helidon.examples.database.mp   

[tvallin]

Fixed by #4556