[GHA] fix coverage check

[pepoviola]

Coverage is failing by disk space

note: /usr/bin/ld: final link failed: No space left on device
          collect2: error: ld returned 1 exit status

LLVM Profile Error: Failed to write file "/home/runner/work/zombienet-sdk/zombienet-sdk/target/llvm-cov-target/zombienet-sdk-10673-12037417312460909353_1.profraw": No space left on device
LLVM Profile Error: Failed to write file "/home/runner/work/zombienet-sdk/zombienet-sdk/target/llvm-cov-target/zombienet-sdk-10673-2618[613](https://github.com/paritytech/zombienet-sdk/actions/runs/8014123313/job/21892341786?pr=167#step:6:614)810332053948_1.profraw": No space left on device
LLVM Profile Error: Failed to write file "/home/runner/work/zombienet-sdk/zombienet-sdk/target/llvm-cov-target/zombienet-sdk-10697-[618](https://github.com/paritytech/zombienet-sdk/actions/runs/8014123313/job/21892341786?pr=167#step:6:619)122074758705362_1.profraw": No space left on device
LLVM Profile Error: Failed to write file "/home/runner/work/zombienet-sdk/zombienet-sdk/target/llvm-cov-target/zombienet-sdk-10697-10606988477790598924_1.profraw": No space left on device
LLVM Profile Error: Failed to write file "/home/runner/work/zombienet-sdk/zombienet-sdk/target/llvm-cov-target/zombienet-sdk-10697-4445821403260916855_1.profraw": No space left on device
LLVM Profile Error: Failed to write file "/home/runner/work/zombienet-sdk/zombienet-sdk/target/llvm-cov-target/zombienet-sdk-10697-10209320367533112091_1.profraw": No space left on device
LLVM Profile Error: Failed to write file "/home/runner/work/zombienet-sdk/zombienet-sdk/target/llvm-cov-target/zombienet-sdk-10697-12441275242637032147_1.profraw": No space left on device

https://github.com/paritytech/zombienet-sdk/actions/runs/8014123313/job/21892341786?pr=167

[pepoviola]

fixed by #172