[CI] Fix Rust permissions for wasmtime and sccache (#10015)

Previously this was ran as part of `ubuntu_install_rust.sh`, as we now have multiple scripts which write as the container build user we have to fix up each time to ensure future users don't break.

Author: Mousius

docker/install/ubuntu_install_rust.sh

@@ -26,5 +26,5 @@ export PATH=$CARGO_HOME/bin:$PATH
 rustup component add rustfmt
 rustup component add clippy
 
-# make rust usable by all users
+# make rust usable by all users after install during container build
 chmod -R a+w /opt/rust

docker/install/ubuntu_install_sccache.sh

@@ -26,3 +26,6 @@ cargo install sccache
 mkdir /opt/sccache
 ln "$(which sccache)" /opt/sccache/cc
 ln "$(which sccache)" /opt/sccache/c++
+
+# make rust usable by all users after install during container build
+chmod -R a+w /opt/rust

docker/install/ubuntu_install_wasmtime.sh

@@ -24,3 +24,6 @@ export WASMTIME_HOME=/opt/wasmtime
 curl https://wasmtime.dev/install.sh -sSf | bash
 export PATH="${WASMTIME_HOME}/bin:${PATH}"
 rustup target add wasm32-wasi
+
+# make rust usable by all users after install during container build
+chmod -R a+w /opt/rust