[release/8.0.3xx-staging] Remove PGO builds

[jkoritzinsky]

Remove the PGO legs in dotnet/installer's official build. We aren't using these assets, and we accidentally regressed production of them in dotnet/runtime. We initially were going to fix this by fixing the jobs in dotnet/runtime, but respinning runtime is expensive at this time so we decided to modify the build here instead.

Customer Impact

• Customer reported
• Found internally

[Select one or both of the boxes. Describe how this issue impacts customers, citing the expected and actual behaviors and scope of the issue. If customer-reported, provide the issue number.]

Regression

• Yes
• No

[If yes, specify when the regression was introduced. Provide the PR or commit if known.]

Regressed with dotnet/runtime#102097

Testing

[How was the fix verified? How was the issue missed previously? What tests were added?]
This is just removing test lanes, so high confidence in the fix.

Risk

[High/Medium/Low. Justify the indication by mentioning how risks were measured and addressed.]

Low risk. We're removing these jobs completely and the PGO assets are the only assets that were produced by these jobs.