Add workflows to README (apache#29096)

* Add readme for PerformanceTests TextIOIT, JDBC, Kafka IO, SpannerIO, SQLBigQueryIO and BiqQueryIO Python

* Update readme

* PRs 28582 28584 28606 28581

* PR 28738 LoadTests_Java_GBK_Dataflow

* Add readme for PostCommit Java Examples Dataflow V2

* Add readme for LoadTests Java CoGBK

* Add readme for LoadTests Python CoGBK Dataflow

* Add readme for LoadTests Python ParDo and SideInput

* Add readme for LoadTests Smoke Python and Java

* Update Readme

* Update Readme

* updated README

* Update readme for Performance Tests BigQueryIO Write Python Batch

* Remove Trigger Phrases for Load Tests and Performance tests

* PR 28846 28730 28827 28861 28897

* update readme

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Co-authored-by: aleksandr-dudko <[email protected]>
Co-authored-by: vitaly.terentyev <[email protected]>
Co-authored-by: magicgoody <[email protected]>