Add documentation for standalone (sparkless) GC #13141

Job	Run time
Check if secrets are available.	1s
Generate code from latest lakeFS app	11s
Build lakeFS HadoopFS	35s
Prepare Spark Apps	38s
Build and push rclone export Docker image	24s
login-to-amazon-ecr	4s
Build and push Docker image	2m 21s
Test lakeFS Hadoop FileSystem	3m 59s
Test lakeFS rclone export functionality	45s
Test lakeFS with Spark 2.X	5m 21s
Test lakeFS multipart upload with Hadoop S3A	1m 25s
Build metadata client for Spark 3.x	10s
Test lakeFS with Spark 3.X	6m 52s
E2E - DynamoDB Local - Local Block Adapter	1m 20s
Test metastore client commands using trino	1m 3s
Test lakeFS against the python wrapper client	1m 35s
Quickstart	2m 41s
Run latest lakeFS app on AWS S3 (false)	7m 16s
Run latest lakeFS app on AWS S3 + Basic Auth	5m 34s
Run latest lakeFS app on AWS S3 (true)	5m 2s
Run latest lakeFS app on AWS S3 DynamoDB KV	4m 57s
Run latest lakeFS app on Azure with Azure blobstore	6m 21s
Run latest lakeFS app on Azure with Azure Data Lake Storage Gen2 and CosmosDB	12m 12s
Run latest lakeFS app on Google Cloud Platform and Google Cloud Storage	8m 11s
Test lakeFS metadata client export with Spark 3.x	1m 29s
Test unified gc	3m 43s
	1h 24m 10s

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