[improve] Configure Rocksdb to use musl libc flavor of the native library

[lhotari]

Motivation

When ROCKSDB_MUSL_LIBC=true is set in environment, it simplifies the logic on RocksDB side for initializing the library: https://github.com/facebook/rocksdb/blob/444b3f4845dd01b0d127c4b420fdd3b50ad56682/java/src/main/java/org/rocksdb/util/Environment.java#L73-L91

The problem with the RocksDB logic is that it executes a shell command to detect that it's running in a musl environment.
This could be a problem when shell commands are restricted due to security reasons.

    // check if ldd indicates a muslc lib
    try {
      final Process p =
          new ProcessBuilder("/usr/bin/env", "sh", "-c", "ldd /usr/bin/env | grep -q musl").start();
      if (p.waitFor() == 0) {
        return true;
      }
    } catch (final IOException | InterruptedException e) {
      // do nothing, and move on to the next check
    }

Modifications

• pass ROCKSDB_MUSL_LIBC=true in the environment for the docker image

Documentation

• doc
• doc-required
• doc-not-needed
• doc-complete

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 74.56%. Comparing base (bbc6224) to head (224202d).
Report is 614 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #23375      +/-   ##
============================================
+ Coverage     73.57%   74.56%   +0.99%     
- Complexity    32624    34485    +1861     
============================================
  Files          1877     1934      +57     
  Lines        139502   145132    +5630     
  Branches      15299    15870     +571     
============================================
+ Hits         102638   108218    +5580     
+ Misses        28908    28621     -287     
- Partials       7956     8293     +337     

Flag	Coverage Δ
inttests	27.49% <ø> (+2.91%)	⬆️
systests	24.50% <ø> (+0.17%)	⬆️
unittests	73.92% <ø> (+1.08%)	⬆️

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see 601 files with indirect coverage changes