Slim ServerMiddleware to `(ctx, call_next)` and add `OpenTelemetryMiddleware` #2915

Job	Run time
checks / pre-commit	46s
checks / readme-snippets	16s
checks / test (3.11, locked, ubuntu-latest)	59s
checks / test (3.10, lowest-direct, windows-latest)	1m 27s
checks / test (3.10, locked, windows-latest)	1m 33s
checks / test (3.12, locked, windows-latest)	1m 39s
checks / test (3.10, locked, ubuntu-latest)	1m 1s
checks / test (3.11, lowest-direct, ubuntu-latest)	1m 9s
checks / test (3.10, lowest-direct, ubuntu-latest)	1m 2s
checks / test (3.11, locked, windows-latest)	1m 27s
checks / test (3.14, locked, windows-latest)	2m 28s
checks / test (3.14, lowest-direct, ubuntu-latest)	57s
checks / test (3.14, locked, ubuntu-latest)	2m 1s
checks / test (3.12, locked, ubuntu-latest)	1m 8s
checks / test (3.13, lowest-direct, windows-latest)	1m 33s
checks / test (3.14, lowest-direct, windows-latest)	1m 37s
checks / test (3.11, lowest-direct, windows-latest)	1m 30s
checks / test (3.12, lowest-direct, windows-latest)	1m 39s
checks / test (3.13, locked, windows-latest)	1m 58s
checks / test (3.12, lowest-direct, ubuntu-latest)	1m 8s
checks / test (3.13, locked, ubuntu-latest)	41s
checks / test (3.13, lowest-direct, ubuntu-latest)	1m 2s
all-green	3s
	29m 4s

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