logger: fix file open issue if crypto algorithm is disabled

[jnippula]

Create empty file even if crypto key is not stored into the beginning of the log file to allow file logger to always append log data into existing file.

Solved Problem

Fixes #24155

Solution

• In case crypto is disabled and there is no key data to be stored into the beginning of the file, just create empty file to make sure the file already exists when logger starts appending log data later on.

Changelog Entry

For release notes:

Bugfix: Fix logger file open when SDLOG_ALGORITHM is 0 (crypto disabled)

Alternatives

Could also add "append" parameter to start_log() function to select whether file needs to be opened as APPEND or CREATE flag.

Test coverage

• Unit/integration test: To be done..