This commit adds test infrastructure for Neo4j repositories through
`@DataNeo4jTest`.

See gh-8618

* pr/8791:
  Update doc for add-application-context-header

Closes gh-8791

This is a test dependency and should be marked as such.

Fixes gh-8789

* pr/8781:
  Polish "Use git.commit.id.abbrev if present" contribution
  Use git.commit.id.abbrev if present

Closes gh-8781

Currently GitProperties always shortens the property git.commit.id to an
hardcoded length of 7.

However, both the Maven plugin git-commit-id-plugin and the Gradle
plugin gradle-git-properties are now providing the property
git.commit.id.abbrev along with the propery git.commit.id.
Moreover, the Maven plugin allows to customize the length of the
abbreviated commit ID with the configuration abbrevLength. The Gradle
plugin doesn't allow (yet) to configure this length.

Closes gh-8773

This reverts commit 51a2d9b1.

See gh-8687

See gh-8589

Closes gh-8769

See commit c5bcefbd in Spring Framework, which refactored
the RequestMappingHandlerAdapter.

Closes gh-8767

This reverts commit 9164265a.

See gh-8589

See gh-8589

See gh-8687

* pr/8660:
  Fix test assertions

Closes gh-8660

* pr/8678:
  Fix propdeps-plugin url in doc

Closes gh-8678

* pr/8698:
  Polish

Closes gh-8698

See gh-8698

* pr/8699:
  Add a missing test for "Fix properties parsing for comment chars"

Closes gh-8699

Closes gh-7968

* pr/8718:
  Fix typo

Closes gh-8718

* pr/8686:
  Replace empty string concatenation with String.valueOf()

Closes gh-8686

Closes gh-8752