Remove deprecated elasticsearch2

[regadas]

related to #2796

[codecov]

Codecov Report

Merging #2800 into 0.9.x will decrease coverage by 1.65%.
The diff coverage is n/a.

@@            Coverage Diff            @@
##           0.9.x    #2800      +/-   ##
=========================================
- Coverage   72.2%   70.55%   -1.66%     
=========================================
  Files        220      220              
  Lines       7481     7481              
  Branches     337      342       +5     
=========================================
- Hits        5402     5278     -124     
- Misses      2079     2203     +124

Impacted Files	Coverage Δ
...scala/com/spotify/scio/bigquery/client/Cache.scala	0% <0%> (-74.08%)	⬇️
.../spotify/scio/bigquery/BigQueryPartitionUtil.scala	0% <0%> (-52.5%)	⬇️
.../spotify/scio/bigquery/client/BigQueryConfig.scala	0% <0%> (-47.06%)	⬇️
.../scala/com/spotify/scio/bigquery/StorageUtil.scala	0% <0%> (-36.85%)	⬇️
...otify/scio/bigquery/syntax/ScioContextSyntax.scala	16.66% <0%> (-36.12%)	⬇️
...com/spotify/scio/bigquery/types/BigQueryType.scala	58.33% <0%> (-29.17%)	⬇️
...com/spotify/scio/bigquery/types/TypeProvider.scala	52.11% <0%> (-22.54%)	⬇️
...la/com/spotify/scio/bigquery/client/BigQuery.scala	28.2% <0%> (-10.26%)	⬇️
...la/com/spotify/scio/bigquery/client/TableOps.scala	0% <0%> (-10.11%)	⬇️
...n/scala/com/spotify/scio/bigquery/BigQueryIO.scala	37.79% <0%> (-4.79%)	⬇️
... and 2 more

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