Review default and blockedlist postgresql.conf

StackGres includes both:

• A default configuration. Parameters here are used unless a specific's user configuration overrides some or all of the values. Source: https://gitlab.com/ongresinc/stackgres/-/blob/development/stackgres-k8s/src/operator/src/main/resources/postgresql-default-values.properties

• A blockedlist, i.e., parameters that belong to the default configuration but can never be overriden by a user's config. Hence, they are always set: https://gitlab.com/ongresinc/stackgres/-/blob/development/stackgres-k8s/src/operator/src/main/resources/postgresql-blacklist.properties

This issue calls for a deep review of both. In particular, among other suggestions, is proposed to:

• Document all the parameters and their values in a table, and explain why each value is proposed.
• Check for missing parameters. For example, we should set some sane defaults in pg_stat_statements.*, given we're including it by default.
• Why the blockedlist only contains the blockedlist, and not the values we're setting by default? Should we include them all in the default list too? Are those in blockedlist not present in defaults using Postgres' own default values? This should be clarified.
• Include final configurations in SG.
• Apply changes required for 1.0.