fix(blooms): Disable metas cache on bloom gateway

[chaudum]

What this PR does / why we need it:

The bloom gateway does not fetch any metas any more since the index gateway resolves them.

Renamed isModuleEnabled() to isTarget(), because the function name is confusing.

Checklist

• Reviewed the CONTRIBUTING.md guide (required)
• Documentation added
• Tests updated
• Title matches the required conventional commits format, see here
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[chaudum]

That is the actual fix to enable the metas cache only on index gateways.

[xiejian06033218]

Hi @chaudum, our loki is running in ssd mode, where index gateway is on backend node, we found that bloom shipper metas cache is not working, probably because your above MR allows only metas cache on index-gateway. therefore, I prepared this MR: #15275, to allow metas cache on backend node, can you please review it? thanks.