Upgrade 4 AIX 72 nodes to TL5 (potentially)

We have 4 aix nodes which are 72 TL2 and are causing quite abit of infrastructure issues related to being EOL. The nodes are
```
build-osuosl-aix72-ppc64-1 7200-02-02-1810
build-osuosl-aix72-ppc64-2 7200-02-02-1810
test-osuosl-aix72-ppc64-3 7200-02-02-1810
test-osuosl-aix72-ppc64-4 7200-02-02-1810
```
See https://github.com/adoptium/infrastructure/issues/4299#issuecomment-4780724095 and the rest of that issue for some of the infra problems caused by those machines.

Ideally I would like to get these upgraded to aix73, but keeping them 72 TL5 is also fine. Jumping the build nodes straight to 73 might be a problem as those 2 build nodes are the only ones we use to build JDKs < 25, so will have to investigate whether these JDKs can be built on 73.

Will speak to the IBM team to see what our options are

Start by reviewing issue 4299 and its referenced comment for the infrastructure problems affecting the four listed AIX 7.2 TL2 nodes. Consult the IBM team about upgrading to AIX 7.3 or TL5, then verify whether the two build nodes can still build JDKs older than 25; done means the selected upgrade is completed without breaking those builds.

Written by the indexing model from the issue text.