Enable revive rules

[aknuds1]

Enable previously disabled revive rules, to harmonize with Prometheus:

• dot-imports
• early-return
• exported
• increment-decrement
• indent-error-flow
• receiver-naming
• unexported-return
• unused-receiver
• var-declaration
• var-naming

Also fixing caught issues.

[Copilot]

Pull Request Overview

This PR enables previously disabled revive linting rules to harmonize with Prometheus standards and fixes the caught linting issues. The changes focus on standardizing receiver naming conventions and improving code quality.

Key changes:

• Enable 10 revive linting rules including receiver-naming, var-naming, and increment-decrement
• Fix receiver parameter names to follow Go conventions (use consistent short names)
• Apply early-return pattern and increment/decrement optimizations

Reviewed Changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
.golangci.yml	Enables previously disabled revive linting rules
server/static_file_server_test.go	Removes unused receiver parameter
model/value_type.go	Standardizes receiver name from 'e' to 'et'
model/value_histogram.go	Changes receiver name from 'b' to 's' for consistency
model/value.go	Changes receiver name from 'mat' to 'm' for brevity
model/time.go	Removes unused receiver parameter
model/metric.go	Removes unused receiver parameter
model/labelset.go	Standardizes receiver names from 'l' to 'ls'
expfmt/text_parse.go	Applies early-return pattern for better flow control
expfmt/expfmt.go	Fixes receiver naming and adds lint suppressions
config/http_config.go	Uses increment operator and removes unused receivers
config/config.go	Removes redundant bool type declaration

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