[CI] enable custom ops build (#466)

### What this PR does / why we need it?
This PR enable custom ops build  by default. 

### Does this PR introduce _any_ user-facing change?

Yes, users now install vllm-ascend from source will trigger custom ops
build step.

### How was this patch tested?
By image build and e2e CI

---------

Signed-off-by: wangxiyuan <wangxiyuan1007@gmail.com>

tools/shellcheck.sh

@@ -39,6 +39,3 @@ if ! [ -x "$(command -v shellcheck)" ]; then
     PATH="$PATH:$(pwd)/shellcheck-${scversion}"
     export PATH
 fi
-
-# TODO - fix warnings in .buildkite/run-amd-test.sh
-find . -name "*.sh" -not -path "./.buildkite/run-amd-test.sh" -print0 | xargs -0 -I {} sh -c 'git check-ignore -q "{}" || shellcheck "{}"'