Remove ineffective argument from sample

[jansauer]

Based on the documentation of the individual env vars, OVERPASS_META only applies on init mode. Since this docker run example is using the clone mode the OVERPASS_META is ineffective and only makes the sample more complex and confusing.

[wiktorn]

OVERPASS_META argument is also used when running update scripts as well as starting dispatcher. I'm not sure, if removing it will not affect the functionality. I do not have necessary infrastructure to test cloned instance.

[jansauer]

Oh, I forgot to think about the update the script.

https://github.com/wiktorn/Overpass-API/blob/b40e83243d8bb6af4f81b8ad0c83fe7f8280abd3/README.md?plain=1#L8

Based on the init mode only line i thought that setting this env var in mode clone does not have any effect. Since I'm running my instance in clone mode and without this setting I will try to understand if this results in any problems for my instance.

@wiktorn thx for the feedback.