Jenkins: audit of any retained individual build jobs to reduce disk usage

Ref: https://github.com/adoptium/infrastructure/issues/3285
```
jenkins@jenkins-hetzner-ubuntu2004:~/jobs$ du -sk build-scripts/jobs/jobs/jobs/jdk* build-scripts/jobs/jobs/jobs/evaluation/jobs/jobs/jobs/jdk* build-scripts/jobs/jobs/jobs/release/jobs/jobs/jobs/jdk*
38483916 build-scripts/jobs/jobs/jobs/jdk
40709196 build-scripts/jobs/jobs/jobs/jdk11u
31727760 build-scripts/jobs/jobs/jobs/jdk17u
9464336 build-scripts/jobs/jobs/jobs/jdk20u
10528416 build-scripts/jobs/jobs/jobs/jdk21
12237780 build-scripts/jobs/jobs/jobs/jdk21u
13770112 build-scripts/jobs/jobs/jobs/jdk22
25356428 build-scripts/jobs/jobs/jobs/jdk8u
3805584 build-scripts/jobs/jobs/jobs/evaluation/jobs/jobs/jobs/jdk
18372 build-scripts/jobs/jobs/jobs/evaluation/jobs/jobs/jobs/jdk11u
4906184 build-scripts/jobs/jobs/jobs/evaluation/jobs/jobs/jobs/jdk17u
5259572 build-scripts/jobs/jobs/jobs/evaluation/jobs/jobs/jobs/jdk20u
4542752 build-scripts/jobs/jobs/jobs/evaluation/jobs/jobs/jobs/jdk21
5025796 build-scripts/jobs/jobs/jobs/evaluation/jobs/jobs/jobs/jdk21u
2300000 build-scripts/jobs/jobs/jobs/evaluation/jobs/jobs/jobs/jdk22
557188 build-scripts/jobs/jobs/jobs/evaluation/jobs/jobs/jobs/jdk23
627552 build-scripts/jobs/jobs/jobs/evaluation/jobs/jobs/jobs/jdk8u
16899976 build-scripts/jobs/jobs/jobs/release/jobs/jobs/jobs/jdk11u
13937892 build-scripts/jobs/jobs/jobs/release/jobs/jobs/jobs/jdk17u
5823836 build-scripts/jobs/jobs/jobs/release/jobs/jobs/jobs/jdk19u
8339712 build-scripts/jobs/jobs/jobs/release/jobs/jobs/jobs/jdk20
6462948 build-scripts/jobs/jobs/jobs/release/jobs/jobs/jobs/jdk20u
6126940 build-scripts/jobs/jobs/jobs/release/jobs/jobs/jobs/jdk21
8507088 build-scripts/jobs/jobs/jobs/release/jobs/jobs/jobs/jdk21u
7039280 build-scripts/jobs/jobs/jobs/release/jobs/jobs/jobs/jdk8u
```
With about 270Gb of space used by build-scripts/jobs (i.e. the individual platform jobs) we should look at which ones are being retained in there and see if they are still required.