Remove wrong LANG from dockerfile use parent default

[ia3andy]

Default in parent is LANG="C.utf8":

• https://catalog.redhat.com/software/containers/ubi8/openjdk-17/618bdbf34ae3739687568813?container-tabs=dockerfile
• https://catalog.redhat.com/software/containers/ubi8/openjdk-11/5dd6a4b45a13461646f677f4?container-tabs=dockerfile

According to https://access.redhat.com/solutions/5211991 , the UBI image has glibc-minimal-langpack is installed by default for C, POSIX and C.UTF-8 locales. To use en_US.utf8, glibc-langpack-en would need to be installed but using LANG="C.utf8" should be ok.

[quarkus-bot[bot]]

Failing Jobs - Building 79d7ed54b396fc045c5313a8fecd0175209bcec7

Status	Name	Step	Failures	Logs	Raw logs
✖	JVM Tests - JDK 11	Build	Failures	Logs	Raw logs
:heavy_check_mark:	JVM Tests - JDK 17
:heavy_check_mark:	JVM Tests - JDK 18
:heavy_check_mark:	Maven Tests - JDK 11
:hourglass:	Maven Tests - JDK 11 Windows	Build	:warning: Check →	Logs	Raw logs

Failures

:gear: JVM Tests - JDK 11 #

- Failing: integration-tests/jpa-oracle integration-tests/reactive-oracle-client 

:package: integration-tests/jpa-oracle

✖ Failed to execute goal io.fabric8:docker-maven-plugin:0.40.1:start (docker-start) on project quarkus-integration-test-jpa-oracle: I/O Error

:package: integration-tests/reactive-oracle-client

✖ Failed to execute goal io.fabric8:docker-maven-plugin:0.40.1:start (docker-start) on project quarkus-integration-test-reactive-oracle-client: I/O Error