Update CI workflows to check Xcode 16.1 and macOS 15

[liamnichols]

• [macOS] Support policy changes; Xcode 14 and 16 will be removed from macOS 14 on November 4 actions/runner-images#10703

This Pull Request updates the workflow configurations to use macOS 15 and Xcode 16.1 as the primary OS for checks.

In addition, some minor adjustments are made reflect changes in runner images as referenced in the ticket linked above.

[github-actions]

✅ Pull Request passed benchmark checks

Summary

Mon Nov 11 15:31:58 UTC 2024

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Threshold deviations for XCStringsToolBenchmarks:StringGenerator.generateSource(for:tableName:accessLevel:)
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Time (total CPU) (ms, Δ)	main	pull_request	Difference Δ	Threshold Δ
p0	292	295	3	0
p25	292	295	3	0
p50	293	296	3	0
p75	293	297	4	0
p90	294	298	4	0
p99	294	298	4	0
p100	294	298	4	0

New baseline 'pull_request' is WORSE than the 'main' baseline thresholds.

---

Comparing results between 'main' and 'pull_request'

Host 'Mac-1731338316905.local' with 3 'arm64' processors with 7 GB memory, running:
Darwin Kernel Version 23.6.0: Wed Jul 31 20:50:13 PDT 2024; root:xnu-10063.141.1.700.5~1/RELEASE_ARM64_VMAPPLE

XCStringsToolBenchmarks

StringGenerator.generateSource(for:tableName:accessLevel:) metrics

Time (total CPU) (ms) *	p0	p25	p50	p75	p90	p99	p100	Samples
main	292	292	293	293	294	294	294	4
pull_request	295	295	296	297	298	298	298	4
Δ	3	3	3	4	4	4	4	0
Improvement %	-1	-1	-1	-1	-1	-1	-1	0