[non-BE]Fixing the output gain for BRs 192kbps and below so that it matches the same...

Basic Info

• Related issues: #977 (closed)
• Requested reviewers: @weckbecker

Reason why this change is needed

• Output gain mismatch for different bit rates in OSBA

Description of the change

• Removed an output gain in the encoder that was applied only for objects in OSBA bitrates 192 kbps and below.
• Added new gain when ISM and SBA are merged so that it matches the output for 256 kbps and above.

Affected operating points

• Non-BE for all OSBA outputs and bitstreams for bit rates 192 kbps and below.