chore: golf some term/rw proofs using linear_combination

[hrmacbeth]

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[github-actions]

PR summary b689439638

Import changes for modified files

No significant changes to the import graph

Import changes for all files

Files	Import difference

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Declarations diff

No declarations were harmed in the making of this PR! 🐙

You can run this locally as follows

## summary with just the declaration names:
./scripts/declarations_diff.sh <optional_commit>

## more verbose report:
./scripts/declarations_diff.sh long <optional_commit>

The doc-module for script/declarations_diff.sh contains some details about this script.

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No changes to technical debt.

You can run this locally as

./scripts/technical-debt-metrics.sh pr_summary

• The relative value is the weighted sum of the differences with weight given by the inverse of the current value of the statistic.
• The absolute value is the relative value divided by the total sum of the inverses of the current values (i.e. the weighted average of the differences).

[hrmacbeth]

!bench

[leanprover-bot]

Here are the benchmark results for commit b689439.
There were no significant changes against commit 06553ac.

[github-actions]

File	Instructions	%
build	-6.574⬝10⁹	(+0.00%)
Mathlib.NumberTheory.Zsqrtd.Basic	-1.333⬝10⁹	(-1.64%)
Mathlib.Analysis.Convex.Slope	-5.489⬝10⁹	(-5.90%)

[grunweg]

I won't approve this yet, as it's still labelled WIP - but from a cursory look, these golfs look great!