[REVIEW] NEXUS-5468: HTTP connection leak in case of LSEx

Fix for LRS to always clean up PreparedContentLocator instances
and a UT verifying this happens in both case, in "norma" but
also in "early unexpected" exception case.

Issue:
https://issues.sonatype.org/browse/NEXUS-5468

CI
https://bamboo.zion.sonatype.com/browse/NXO-OSSF2-1