Remove Rust and point integration tests to arrow-rs repo

[alamb]

Note: migrated from original JIRA: https://issues.apache.org/jira/browse/ARROW-12444

Goals:

• Make integration tests run against arrow-rs@master
• Remove Rust from apache/arrow

Tasks:

• Remove Rust from CI
• Remove rust/
• git clone apache/arrow-rs@master in integration tests
• remove rust from Archery Lint
• remove rust from PR labeler
• remove rust from detect_changes.py

[alamb]

Comment from Jorge Leitão(jorgecarleitao) @ 2021-04-19T04:07:08.720+0000:

cc [~andygrove] [~wes] [~alamb] [~kszucs]

Comment from Andrew Lamb(alamb) @ 2021-04-19T09:50:11.144+0000:

I recommend that we make integration tests from apache/arrow@master run against a specific pin of arrow-rs rather than master. The rationale being that if integration runs always against master unintentional breakages to arrow can be introduced at seemingly random times, leading to frustration and harder to debug errors

With the specific pin approach we will have to increase the pin at some period of time, but we will have control over the schedule and will know exactly what versions were tested to be compatible

[jorgecarleitao]

Closing and reopened the JIRA one, since this operation will be done in apache/arrow