Stop initialising rust submodules, travis does this for us

Fixes #24630.

.travis.yml

@@ -93,8 +93,6 @@ install:
   - if [[ "$RUST_OPTIONS" != "" ]]; then rustc --version; fi
   - if [[ "$RUST_OPTIONS" != "" ]]; then cargo --version; fi
   ## If we're testing rust builds in offline-mode, then set up our vendored dependencies
-  - if [[ "$RUST_OPTIONS" == "--enable-rust" ]]; then git submodule init  ; fi
-  - if [[ "$RUST_OPTIONS" == "--enable-rust" ]]; then git submodule update; fi
   - if [[ "$TOR_RUST_DEPENDENCIES" == "true" ]]; then export TOR_RUST_DEPENDENCIES=$PWD/src/ext/rust/crates; fi
 
 script: