Remove the OSS UBI builds (#49118)

This commit removes the OSS UBI-based Docker images from the build as we
are not going to publish these images for the time being.

distribution/docker/oss-ubi-docker-build-context/build.gradle

@@ -1,11 +0,0 @@
-apply plugin: 'base'
-
-task buildOssUbiDockerBuildContext(type: Tar) {
-  extension = 'tar.gz'
-  compression = Compression.GZIP
-  archiveClassifier = "docker-build-context"
-  archiveBaseName = "elasticsearch-oss-ubi7"
-  with dockerBuildContext(true, true, false)
-}
-
-assemble.dependsOn buildOssUbiDockerBuildContext

distribution/docker/oss-ubi-docker-export/build.gradle

@@ -1,2 +0,0 @@
-// This file is intentionally blank. All configuration of the
-// export is done in the parent project.

settings.gradle

@@ -32,8 +32,6 @@ List projects = [
   'distribution:docker:docker-export',
   'distribution:docker:oss-docker-build-context',
   'distribution:docker:oss-docker-export',
-  'distribution:docker:oss-ubi-docker-build-context',
-  'distribution:docker:oss-ubi-docker-export',
   'distribution:docker:ubi-docker-build-context',
   'distribution:docker:ubi-docker-export',
   'distribution:packages:oss-deb',