Fix test MojDbShardManagerTest

:Release Notes:
add testing mode to device id trace cache

:Detailed Notes:

:Testing Performed:
tested on build

:QA Notes:

:Issues Addressed:
[GF-23884] Unit test failed: MojDbShardManagerTest

Open-webOS-DCO-1.0-Signed-off-by: Igor Kuksyuk <ikuksyuk@luxoft.com>

Change-Id: Ibdfddc6906591e7085e1debb6a18c54a939607b5
Reviewed-on: https://g2g.palm.com/3216
Reviewed-by: Build Verification
Reviewed-by: Igor Kuksyuk <ikuksyuk@luxoft.com>
Tested-by: Igor Kuksyuk <ikuksyuk@luxoft.com>
Reviewed-by: Maksym Sditanov <maxim.sditanov@lge.com>
Reviewed-by: Roger Stringer <roger.stringer@lge.com>