ARROW-12435: [Rust][DataFusion] Remove unnecessary references to namespace in executor

[edrevo]

No description provided.

[github-actions]

https://issues.apache.org/jira/browse/ARROW-12435

[codecov-commenter]

Codecov Report

❗ No coverage uploaded for pull request base (master@fdd6ab1). Click here to learn what that means.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master   #10084   +/-   ##
=========================================
  Coverage          ?   78.91%           
=========================================
  Files             ?      286           
  Lines             ?    64717           
  Branches          ?        0           
=========================================
  Hits              ?    51070           
  Misses            ?    13647           
  Partials          ?        0           

Impacted Files	Coverage Δ
rust/datafusion/src/execution/context.rs	92.60% <ø> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update fdd6ab1...3068c85. Read the comment docs.

[alamb]

I think CI for SIMD tests is failing due to flatbuffer issues -- @andygrove fixed in in #10081

[alamb]

The Apache Arrow Rust community is moving the Rust implementation into its own dedicated github repositories arrow-rs and arrow-datafusion. It is likely we will not merge this PR into this repository

Please see the mailing-list thread for more details

We expect the process to take a few days and will follow up with a migration plan for the in-flight PRs.