Remove ICU4C pinned version

Description

ICU4C version 76 breaks gitlab-elasticsearch-indexer-update. We set ICU4C to version 75 !4172 (closed) until the issue is fixed. In parallel, we are removing ICU4C dependency from Elasticsearch Indexer gitlab#502388, gitlab-elasticsearch-indexer!537 (closed).

If there are no issues, we should remove the ICU4C pinned version.

Test

make gitlab-elasticsearch-indexer-update