Remove ambiguity from result file matching

We observed that in some cases, the wrong result file will be picked if the MPA number appears in the date/time stamp of a later MPA's results.

For example, the call

ls ../Results_MPATesting/QPT_44682_001R/mpa_test_*_10_*_mask_test.csv

matches both of these files, the correct one for MPA 10 and another from MPA 11

../Results_MPATesting/QPT_44682_001R/mpa_test_QPT_44682_001R_10_2025_06_19_15_06_27_mask_test.csv
../Results_MPATesting/QPT_44682_001R/mpa_test_QPT_44682_001R_11_2025_06_19_15_10_29_mask_test.csv

In this case this lead to the MaPSA being flagged as Grade C because that specific result file for MPA 11 contained unmaskable pixels.

The changes in this MR prevent numbers in the date/time stamp to be included in the matching and resolves this issue.