Take into account that attach_dimscales can fail when dimensions and variables are named inconsistently

[Alexander-Barth]

This PR addresses issue #2962.

All tests pass locally:

...
227/231 Test #227: nczarr_test_run_fillonlyz .................   Passed    0.08 sec
        Start 228: nczarr_test_run_nczfilter
228/231 Test #228: nczarr_test_run_nczfilter .................   Passed    0.07 sec
        Start 229: nczarr_test_run_filter
229/231 Test #229: nczarr_test_run_filter ....................   Passed    0.39 sec
        Start 230: nczarr_test_run_specific_filters
230/231 Test #230: nczarr_test_run_specific_filters ..........   Passed    0.43 sec
        Start 231: nczarr_test_run_filter_vlen
231/231 Test #231: nczarr_test_run_filter_vlen ...............   Passed    0.13 sec

100% tests passed, 0 tests failed out of 231

Total Test time (real) = 219.58 sec