[CI] set errexit in config validate
[CI] set errexit in config validate

The config validate wordflow relies on re-building the configs in
place and diff-ing them in git. There is a loophole where the diff-ing
doesn't detect changes because the config fails to re-build. Switch on
errexit so that it detects when config fails to re-build.

Closes: #1826
Approved by: davidiw

aptos-labs/aptos-core,aptos-labs/aptos-core,libra/libra,libra/libra,aptos-labs/aptos-core,aptos-labs/aptos-core,libra/libra,libra/libra,aptos-labs/aptos-core,libra/libra,aptos-labs/aptos-core,aptos-labs/aptos-core