[BigQueryWorkloadTester] Tweak the user-agent.

[mirons-google]

s/bigquery-workload-tester/bigquery-workload/

[codecov[bot]]

Codecov Report

Merging #214 into dev will decrease coverage by 4.71%. The diff coverage is n/a.

@@             Coverage Diff              @@
##                dev     #214      +/-   ##
============================================
- Coverage     82.97%   78.25%   -4.72%     
- Complexity      203      547     +344     
============================================
  Files            34       68      +34     
  Lines          1104     4360    +3256     
  Branches         66      332     +266     
============================================
+ Hits            916     3412    +2496     
- Misses          179      848     +669     
- Partials          9      100      +91

Impacted Files	Coverage Δ	Complexity Δ
...tem/benchmark/backends/BigQueryBackendFactory.java	0% <ø> (ø)	0 <0> (ø)	:arrow_down:
.../cloud/pontem/BaseCloudSpannerDatabaseRestore.java	87.93% <0%> (ø)	22% <0%> (?)
.../cloud/pontem/AvroCloudSpannerDatabaseRestore.java	0% <0%> (ø)	0% <0%> (?)
...loud/pontem/FormatStructAsGenericRecordFnTest.java	100% <0%> (ø)	10% <0%> (?)
...oud/pontem/AvroCloudSpannerDatabaseBackupTest.java	100% <0%> (ø)	3% <0%> (?)
...ntem/CloudSpannerDatabaseBackupIntegrityCheck.java	53.52% <0%> (ø)	8% <0%> (?)
...tem/FormatSpannerTablesListStructAsTextFnTest.java	100% <0%> (ø)	4% <0%> (?)
...java/com/google/cloud/pontem/TableInformation.java	87.71% <0%> (ø)	16% <0%> (?)
...CloudSpannerDatabaseRestoreIntegrityCheckTest.java	95.65% <0%> (ø)	5% <0%> (?)
...rc/test/java/com/google/cloud/pontem/UtilTest.java	92.3% <0%> (ø)	4% <0%> (?)
... and 25 more