Miscellaneous HIR typeck nits

[compiler-errors]

Remove some check functions that only have one usage

Also remove Expectation::IsLast, which was both undocumented, and was also made redundant by my cleanup/fix in #103987 😸

[rustbot]

r? @oli-obk

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[oli-obk]

@bors r+ rollup

[bors]

📌 Commit aa41c98 has been approved by oli-obk

It is now in the queue for this repository.

[bors]

⌛ Testing commit aa41c98 with merge a922d1c...

[bors]

☀️ Test successful - checks-actions
Approved by: oli-obk
Pushing a922d1c to master...

[rust-timer]

Finished benchmarking commit (a922d1c): comparison URL.

Overall result: no relevant changes - no action needed

@rustbot label: -perf-regression

Instruction count

This benchmark run did not return any relevant results for this metric.

Max RSS (memory usage)

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	1.1%	[1.1%, 1.1%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-2.8%	[-2.8%, -2.8%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-0.8%	[-2.8%, 1.1%]	2

Cycles

This benchmark run did not return any relevant results for this metric.

Binary size

This benchmark run did not return any relevant results for this metric.

Bootstrap: 650.791s -> 649.583s (-0.19%)