rsz: Buffering and sizing improvements

[openroad-ci]

This PR combines a number of related resizer changes impacting QoR:

• Improvements to gain buffering (repair_design -buffer_gain)
• Pre-selection of buffers used for repair to filter out slow and delay buffers (except for hold repair)
• Replacing resize to target slew with a fanout-of-4 rule
• Restructuring of repair_design to do minimal resizing in response to a violation

It supersedes #6332

[povik]

Dashboard link for when this PR is combined with appropriate flow script changes: https://dashboard.precisioninno.com/compare?sourceAType=Commit&sourceBType=Commit&sourceBName=3ac73fd1cbba34b80953390fc9412c84c3921133&sourceBID=16&sourceAName=c6905f5d5dab4c61d923ba4f164eb2335359cba9&sourceAID=5004

[github-actions]

clang-tidy made some suggestions

[maliberty]

09:38:53  The following tests FAILED:
09:38:53  	366 - gpl.convergence01.tcl (Failed)
09:38:53  	367 - gpl.convergence01.py (Failed)
09:38:53  	389 - gpl.simple01-td.tcl (Failed)
09:38:53  	390 - gpl.simple01-td.py (Failed)
09:38:53  	391 - gpl.simple01-td-tune.tcl (Failed)
09:38:53  	392 - gpl.simple01-td-tune.py (Failed)

needs attention

[github-actions]

clang-tidy review says "All clean, LGTM! 👍"

[github-actions]

clang-tidy review says "All clean, LGTM! 👍"

[povik]

After updates the QoR from this change has degraded: https://dashboard.precisioninno.com/compare?sourceAType=Commit&sourceBType=Commit&sourceBName=3a4a4b5c10a7f036120c4bae4be4e69c1c346062&sourceBID=21&sourceAName=a2e7a0fe4d14cb0382446a3843ee594f696f7de8

I'll need to investigate.

[povik]

After updates the QoR from this change has degraded: https://dashboard.precisioninno.com/compare?sourceAType=Commit&sourceBType=Commit&sourceBName=3a4a4b5c10a7f036120c4bae4be4e69c1c346062&sourceBID=21&sourceAName=a2e7a0fe4d14cb0382446a3843ee594f696f7de8

I'll need to investigate.

I've found the cause: getSwappableCells stopped returning the original size. I would've wished this came with more of a warning.

[github-actions]

clang-tidy review says "All clean, LGTM! 👍"

[github-actions]

clang-tidy review says "All clean, LGTM! 👍"

[povik]

CI green

[maliberty]

Is there an ORFS PR that goes with this or can it be merged as is?

[povik]

It requires metric updates, possibly resolving gf12/ariane congestion. I will pick this up in the morning. If you don't mind the transient secure CI failure this can be merged right away.

[povik]

The ariane congestion is due to buffer placement into bottom left corner. It doesn't happen on master, I'm investigating.

[gudeh]

this is gpl's fault!

[povik]

GPL_KEEP_OVERFLOW=0 works as a workaround to fix ariane in CI