Drop support for old (insecure) fingerprint format

[s-hadinger]

Description:

After 3 years, there shouldn't be any old format fingerprints out there. Drop support for automatic conversion from old to new fingerprint format. This is disabled with #define before removing the code.

See #10571

Checklist:

• The pull request is done against the latest development branch
• Only relevant files were touched
• Only one feature/fix was added per PR and the code change compiles without warnings
• The code change is tested and works with Tasmota core ESP8266 V.2.7.6
• The code change is tested and works with Tasmota core ESP32 V.2.0.14
• I accept the CLA.

NOTE: The code change must pass CI tests. Your PR cannot be merged unless tests pass