Remove escaping when converting EasyBuildError to a string

[Flamefire]

This is especially useful for Pytorch tests where the error message contains formatted output which becomes hard to read:

== FAILED: Installation ended unsuccessfully: An error was raised during test step: 'Failing because not all failed tests could be determined. Tests failed to start, crashed or the test accounting in the PyTorch EasyBlock needs updating!\nMissing: distributed/test_c10d_nccl\nYou can check the test failures (in the log) manually and if they are harmless, use --ignore-test-failure to make the test step pass.\n109 test failures, 0 test errors (out of 262294):\nFailed tests (suites/files):\n\tdistributed/test_symmetric_memory (23 failed, 20 passed, 1 skipped, 0 errors)\n\tdynamo/test_misc (1 failed, 539 passed, 12 skipped, 0 errors)\n\tdynamo/test_utils (1 failed, 7 passed, 0 skipped, 0 errors)\n\tinductor/test_codecache (1 failed, 110 passed, 3 skipped, 0 errors)\n\tinductor/test_cudacodecache (3 failed, 0 passed, 0 skipped, 0 errors)\n\tinductor/test_cutlass_backend (39 failed, 1 passed, 2 skipped, 0 errors)\n\tinductor/test_fp8 (40 failed, 149 passed, 72 skipped, 0 errors)\n\tinductor/test_torchinductor_dynamic_shapes (1 failed, 1527 passed, 71 skipped, 0 errors)\nCould not count failed tests for the following test suites/files:\n\tdistributed/test_c10d_nccl (Undetected or did not run properly)' (took 64 hours 17 mins 9 secs)