`BLE_SECURITY_DATABASE_FILESYSTEM` macro default value

[16L-YT]

Description of defect

the macro BLE_SECURITY_DATABASE_FILESYSTEM has a default value of true and this always through an error in the logs whenever file system is not used (for example I'm using KV store). So, I think it is better to switch the default value to false. I'm I right?. If yes, then I will create a PR.

Target(s) affected by this defect ?

Issue does not seem to be target specific.

Toolchain(s) (name and version) displaying this defect ?

gcc version 10.2.1 20201103 (release) (xPack GNU Arm Embedded GCC, 64-bit)

What version of Mbed-os are you using (tag or sha) ?

mbed-os-6.9.0

What version(s) of tools are you using. List all that apply (E.g. mbed-cli)

Mbed Studio 1.4.1

How is this defect reproduced ?

Get the log with/without default value of BLE_SECURITY_DATABASE_FILESYSTEM, while selecting "ble.ble-security-database-kvstore" : true.

[paul-szczepanek-arm]

Filesystem db is on by default. This is intentional and changing it now would be a breaking change. The error however was not intetional and I made a fix #14921 for that