fix: Add `is_finished` and correct `is_empty` semantics in `RequestQueueClient` #733

Job	Run time
PR title check	4s
Checks / Spell check	6s
Checks / Package check	41s
Checks / Actions lint check	31s
Checks / Lint check / Lint check (3.10)	34s
Checks / Doc check / Docs check	1m 41s
Checks / Lint check / Lint check (3.11)	33s
Checks / Lint check / Lint check (3.14)	31s
Checks / Type check / Type check (3.11)	36s
Checks / Unit tests / Unit tests (ubuntu-latest, 3.13)	5m 2s
Checks / Unit tests / Unit tests (windows-latest, 3.10)	6m 27s
Checks / Type check / Type check (3.10)	30s
Checks / Type check / Type check (3.12)	32s
Checks / Type check / Type check (3.14)	34s
Checks / Unit tests / Unit tests (windows-latest, 3.13)	5m 46s
Checks / Type check / Type check (3.13)	34s
Checks / Unit tests / Unit tests (windows-latest, 3.14)	5m 30s
Checks / Unit tests / Unit tests (macos-latest, 3.10)	5m 7s
Checks / Lint check / Lint check (3.12)	29s
Checks / Unit tests / Unit tests (ubuntu-latest, 3.10)	5m 2s
Checks / Unit tests / Unit tests (windows-latest, 3.12)	6m 37s
Checks / Unit tests / Unit tests (ubuntu-latest, 3.11)	4m 50s
Checks / Unit tests / Unit tests (windows-latest, 3.11)	8m 24s
Checks / Unit tests / Unit tests (ubuntu-latest, 3.14)	3m 52s
Checks / Unit tests / Unit tests (macos-latest, 3.11)	6m 32s
Checks / Unit tests / Unit tests (macos-latest, 3.14)	6m 3s
Checks / Unit tests / Unit tests (macos-latest, 3.12)	9m 8s
Checks / Unit tests / Unit tests (ubuntu-latest, 3.12)	5m 22s
Checks / Lint check / Lint check (3.13)	38s
Checks / Unit tests / Unit tests (macos-latest, 3.13)	3m 45s
	1h 36m 1s

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