Set correct OTA URL for all Tasmota build env

[Jason2866]

Description:

The OTA_URL is now set in the PIO env. The attempts to do where not working in the past since the define (which is a Macro) was extended wrong.

By using the syntax -D DEFINE_NEEDED='"string"' the Macro is parsed and extended correctly.

All #define OTA_URL are removed in source code!
All [env) need to have -DOTA_URL='"path_to_ota_file"' or an empty entry -DOTA_URL='""'

This Option makes it possible to define more settings without the need of user_config_override.h.

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.2.7.4.9
• The code change is tested and works with Tasmota core ESP32 V.2.0.6
• I accept the CLA.

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

[barbudor]

Nice 👍