Merge rust-bitcoin/rust-secp256k1#785: Rearrange tests for `XOnlyPubl… #1612

Job	Run time
Test 32-bit version	21s
Format - nightly toolchain	12s
Docs - stable toolchain (recent)	13s
Test - 1.63.0 toolchain (minimal)	4m 14s
Prepare	3s
Test - 1.63.0 toolchain (recent)	4m 16s
Test - stable toolchain (minimal)	2m 58s
Test - stable toolchain (recent)	3m 1s
WASM - stable toolchain	1m 43s
Test - nightly toolchain (minimal)	2m 30s
Test - nightly toolchain (recent)	2m 24s
Docs - nightly toolchain (recent)	30s
ASAN - nightly toolchain (recent)	1m 27s
Bench - nightly toolchain (recent)	24s
Lint - nightly toolchain (recent)	32s
no-std - nightly toolchain (recent)	47s
	25m 35s

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