Added a slightly more helpful error message to the reads filter

[jamesemery]

Fixes #7944

[gatk-bot]

Github actions tests reported job failures from actions build 2679127706 Failures in the following jobs:

Test Type	JDK	Job ID	Logs
unit	11	2679127706.13	logs
unit	8	2679127706.1	logs

[codecov[bot]]

Codecov Report

Merging #7947 (413983a) into master (e81a361) will decrease coverage by 40.864%. The diff coverage is 100.000%.

:exclamation: Current head 413983a differs from pull request most recent head 7791882. Consider uploading reports for the commit 7791882 to get more accurate results

@@               Coverage Diff                @@
##              master     #7947        +/-   ##
================================================
- Coverage     86.981%   46.116%   -40.864%     
+ Complexity     36962     24011     -12951     
================================================
  Files           2221      2217         -4     
  Lines         173894    173851        -43     
  Branches       18785     18792         +7     
================================================
- Hits          151254     80174     -71080     
- Misses         15998     87790     +71792     
+ Partials        6642      5887       -755     

Impacted Files	Coverage Δ
.../hellbender/engine/filters/CountingReadFilter.java	60.215% <100.000%> (-39.785%)	:arrow_down:
...broadinstitute/hellbender/utils/svd/SimpleSVD.java	0.000% <0.000%> (-100.000%)	:arrow_down:
...titute/hellbender/utils/UnvalidatingGenomeLoc.java	0.000% <0.000%> (-100.000%)	:arrow_down:
...itute/hellbender/utils/locusiterator/LIBSTest.java	0.000% <0.000%> (-100.000%)	:arrow_down:
...ute/hellbender/tools/htsgetreader/HtsgetClass.java	0.000% <0.000%> (-100.000%)	:arrow_down:
...te/hellbender/tools/htsgetreader/HtsgetFormat.java	0.000% <0.000%> (-100.000%)	:arrow_down:
...ender/utils/svd/ApacheSingularValueDecomposer.java	0.000% <0.000%> (-100.000%)	:arrow_down:
...ender/utils/svd/OjAlgoSingularValueDecomposer.java	0.000% <0.000%> (-100.000%)	:arrow_down:
...nder/utils/downsampling/FractionalDownsampler.java	0.000% <0.000%> (-100.000%)	:arrow_down:
...der/cmdline/programgroups/ExampleProgramGroup.java	0.000% <0.000%> (-100.000%)	:arrow_down:
... and 1144 more

[jamesemery]

@droazen I fixed the tests. Can you take a look? I know you have opinions