chore(pom.xml): upgrade to testcontainers 2 to address docker API issue

[vringar]

Description

When upgrading my docker to the latest version suddenly test containers started failing due to https://github.com/testcontainers/testcontainers-java/issues/11212

I'm bumping the dependencies here to address this issue.

Note: As upgrading removed the availability of hamcrest and Junit4, we had to migrate everything to Junit5

Checklist

• [X] PR has a milestone or the no milestone label.
• [X] Backport labels are added if these code changes should be backported. No backport label is added to the latest release, as this branch will be rebased onto main before the next release.

[sbuettner]

@johnBgood can you take a second look?

I was unsure about these changes: https://github.com/camunda/connectors/pull/5736/files#diff-b85f51fcaca955111594f8e075be62eca94510cdd989646eba51f7adf24d0849R94

https://github.com/camunda/connectors/pull/5736/files#diff-8e7f5f8920ad5cd5da9d875f3f9bd16b151d105f74d4db266219b31adb30b6abL91

https://github.com/camunda/connectors/pull/5736/files#diff-8e7f5f8920ad5cd5da9d875f3f9bd16b151d105f74d4db266219b31adb30b6abL132

[johnBgood]

I was unsure about these changes

@sbuettner why? do you see any problem with this change?

[sbuettner]

No, just curious whether they made sense or not.

[team-connectors-int-automation[bot]]

Backport failed for release/8.6, because it was unable to cherry-pick the commit(s).

Please cherry-pick the changes locally and resolve any conflicts.

git fetch origin release/8.6
git worktree add -d .worktree/backport-5736-to-release/8.6 origin/release/8.6
cd .worktree/backport-5736-to-release/8.6
git switch --create backport-5736-to-release/8.6
git cherry-pick -x 08dd6d6cdedaf4a0523510fe0e68d87c73005fad

[team-connectors-int-automation[bot]]

Backport failed for release/8.7, because it was unable to cherry-pick the commit(s).

Please cherry-pick the changes locally and resolve any conflicts.

git fetch origin release/8.7
git worktree add -d .worktree/backport-5736-to-release/8.7 origin/release/8.7
cd .worktree/backport-5736-to-release/8.7
git switch --create backport-5736-to-release/8.7
git cherry-pick -x 08dd6d6cdedaf4a0523510fe0e68d87c73005fad

[team-connectors-int-automation[bot]]

Backport failed for release/8.8, because it was unable to cherry-pick the commit(s).

Please cherry-pick the changes locally and resolve any conflicts.

git fetch origin release/8.8
git worktree add -d .worktree/backport-5736-to-release/8.8 origin/release/8.8
cd .worktree/backport-5736-to-release/8.8
git switch --create backport-5736-to-release/8.8
git cherry-pick -x 08dd6d6cdedaf4a0523510fe0e68d87c73005fad