**What changes were proposed in this pull request?**

Use Hadoop 2.6.5 for the Hadoop 2.6 profile, I see a bunch of fixes including security ones in the release notes that we should pick up

**How was this patch tested?**

Running the unit tests now with IBM's SDK for Java and let's see what happens with OpenJDK in the community builder - expecting no trouble as it is only a minor release.

Author: Adam Roberts <aroberts@uk.ibm.com>

Closes #16616 from a-roberts/Hadoop265Bumper.