[ECO-2111] Fix start version behavior, add web_anon postgrest user

[xbtmatt]

• Add web_anon postgrest user
• Change config.rs starting version field name to: MINIMUM_STARTING_VERSION instead of STARTING_VERSION
• Use the max(a, b) value of MINIMUM_STARTING_VERSION from the config.yaml file field value vs. the processor's latest processed version
• Note this means we have to change the compose.yaml file to pass in MINIMUM_STARTING_VERSION instead of STARTING_VERSION
• This removes the bash code logic from having to query the database (since it's actually already done in the indexer) and uses a clearer env var name to indicate what the field actually does
• To summarize: we now take the minimum value between the config starting version and the latest processed starting version. It's determined entirely inside the processor with no logic in a bash script (which was prone to errors before).