### What this PR does / why we need it?
This pull request addresses several issues within the openEuler
Dockerfiles : `Dockerfile.a3.openEuler` and `Dockerfile.openEuler` to
ensure correct installation and setup of the Mooncake dependency. The
changes primarily involve fixing incorrect file paths for the
mooncake_installer.sh script and streamlining the declaration of the
MOONCAKE_TAG build argument, leading to more robust and accurate
container builds.
### Does this PR introduce _any_ user-facing change?
### How was this patch tested?
- vLLM version: v0.16.0
- vLLM main:
15d76f74e2
Signed-off-by: wjunLu <wjunlu217@gmail.com>
64fba51275