[BigQueryWorkloadTester] Per PM's feedback updating the BigQuery Workload Tester so the ratios used in the Ratio Based Benchmark can be provided in the config file

[codecov[bot]]

Codecov Report

Merging #212 into dev will decrease coverage by 0.45%. The diff coverage is 65.38%.

@@             Coverage Diff              @@
##                dev     #212      +/-   ##
============================================
- Coverage     83.65%   83.19%   -0.46%     
- Complexity      198      203       +5     
============================================
  Files            34       34              
  Lines          1083     1101      +18     
  Branches         64       66       +2     
============================================
+ Hits            906      916      +10     
- Misses          168      176       +8     
  Partials          9        9

Impacted Files	Coverage Δ	Complexity Δ
...om/google/cloud/pontem/BigQueryWorkloadTester.java	0% <0%> (ø)	0 <0> (ø)	:arrow_down:
.../com/google/cloud/pontem/config/Configuration.java	0% <0%> (ø)	0 <0> (ø)	:arrow_down:
.../pontem/benchmark/RatioBasedWorkloadBenchmark.java	100% <100%> (ø)	8 <1> (+2)	:arrow_up:
...tem/benchmark/RatioBasedWorkloadBenchmarkTest.java	97.35% <75%> (-2.65%)	21 <3> (+3)