Fix parachain validator metric (#2328) #7981

Job	Run time
Self-hosted: Linux: gcc-13 coverage/sonar	0s
Self-hosted docker: Build Debug	12m 40s
Self-hosted: Linux: gcc-13 ASAN	36m 17s
Self-hosted docker: Build Release	11m 37s
Self-hosted: Linux: clang-19 TSAN WAVM	30m 8s
Linux: clang-tidy	2m 30s
Self-hosted docker: Build RelWithDebInfo	10m 29s
Self-hosted: Linux: clang-19 UBSAN	8m 27s
${{ matrix.options.name }}	0s
MacOS: Build Debug	12m 19s
MacOS: Build Release	19m 0s
MacOS WAVM: Build Debug	14m 58s
Zombie-Tests (PVF preparation & execution time, test-polkadot-functional-0001-parachains-pvf)	30m 18s
Zombie-Tests (BEEFY voting and finality, test MMR proofs. Assumes Rococo sessions of 1 minute, te...	6m 19s
Zombie-Tests (Test if disputes triggered on finalized blocks within scope always end as valid, te...	6m 57s
Zombie-Tests (Test if disputes triggered on finalized blocks out of scope never get to be confirm...	7m 1s
Zombie-Tests (Approval voting coalescing does not lag finality, test-polkadot-functional-0009-app...	7m 27s
Zombie-Tests (Test we are producing blocks at 6 seconds clip, test-polkadot-functional-0011-async...	7m 5s
Zombie-Tests (Systematic chunk recovery is used if the chunk mapping feature is enabled., test-po...	11m 10s
Zombie-Tests (Warp sync from polkadot node, test-custom-0001-validators-warp-sync)	5m 22s
	4h 0m 4s

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