ansible: add POWER 8 compatibility VMs

[richardlau]

Add test-ibm-rhel8-ppc64_le-2 and test-ibm-rhel8-ppc64_le-3.

Refs: #4405

[richardlau]

Some CIs on the new machines

test-ibm-rhel8-ppc64_le-2:

• v24.x: https://ci.nodejs.org/job/node-test-commit-v8-linux/7278/nodes=rhel8-ppc64le,v8test=v8test/

test-ibm-rhel8-ppc64_le-3:

• v24.x: https://ci.nodejs.org/job/node-test-commit-plinux/64957/nodes=rhel8-ppc64le/ ✅
• node/#6714 (v22.x): https://ci.nodejs.org/job/node-test-commit-plinux/nodes=rhel8-ppc64le/64961/

[sxa]

The v24.x run above failed likely due to memory exhaustion due to runnign with -j32. I've modified the V8 build job to set JOBS only if it's not already set:

export JOBS=${JOBS:-$(getconf _NPROCESSORS_ONLN)}

and defined JOBS to a suitable number on the jenkins agent config for the new nodes. Re-running at https://ci.nodejs.org/job/node-test-commit-v8-linux/7289/