[confmap] Remove stable confmap.unifyEnvVarExpansion feature gate (#11007)

#### Description

Removes stable `confmap.unifyEnvVarExpansion` feature gate.

Author: TylerHelmuth

.chloggen/confmap-remove-unify-feature-gate.yaml

@@ -0,0 +1,25 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: breaking
+
+# The name of the component, or a single word describing the area of concern, (e.g. otlpreceiver)
+component: confmap
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Removes stable `confmap.unifyEnvVarExpansion` feature gate.
+
+# One or more tracking issues or pull requests related to the change
+issues: [11007]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:
+
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: []

internal/globalgates/globalgates.go

@@ -5,12 +5,6 @@ package globalgates // import "go.opentelemetry.io/collector/internal/globalgate
 
 import "go.opentelemetry.io/collector/featuregate"
 
-var UseUnifiedEnvVarExpansionRules = featuregate.GlobalRegistry().MustRegister("confmap.unifyEnvVarExpansion",
-	featuregate.StageStable,
-	featuregate.WithRegisterFromVersion("v0.103.0"),
-	featuregate.WithRegisterToVersion("v0.109.0"),
-	featuregate.WithRegisterDescription("`${FOO}` will now be expanded as if it was `${env:FOO}` and no longer expands $ENV syntax. See https://github.com/open-telemetry/opentelemetry-collector/blob/main/docs/rfcs/env-vars.md for more details. When this feature gate is stable, expandconverter will be removed."))
-
 var NoopTracerProvider = featuregate.GlobalRegistry().MustRegister("service.noopTracerProvider",
 	featuregate.StageAlpha,
 	featuregate.WithRegisterFromVersion("v0.107.0"),

otelcol/command.go

@@ -10,7 +10,6 @@ import (
 	"github.com/spf13/cobra"
 
 	"go.opentelemetry.io/collector/featuregate"
-	"go.opentelemetry.io/collector/internal/globalgates"
 )
 
 // NewCommand constructs a new cobra.Command using the given CollectorSettings.
@@ -55,7 +54,7 @@ func updateSettingsUsingFlags(set *CollectorSettings, flags *flag.FlagSet) error
 		return errors.New("at least one config flag must be provided")
 	}
 
-	if globalgates.UseUnifiedEnvVarExpansionRules.IsEnabled() && set.ConfigProviderSettings.ResolverSettings.DefaultScheme == "" {
+	if set.ConfigProviderSettings.ResolverSettings.DefaultScheme == "" {
 		set.ConfigProviderSettings.ResolverSettings.DefaultScheme = "env"
 	}
 

otelcol/go.mod

@@ -13,7 +13,6 @@ require (
 	go.opentelemetry.io/collector/exporter v0.108.1
 	go.opentelemetry.io/collector/extension v0.108.1
 	go.opentelemetry.io/collector/featuregate v1.14.1
-	go.opentelemetry.io/collector/internal/globalgates v0.108.1
 	go.opentelemetry.io/collector/processor v0.108.1
 	go.opentelemetry.io/collector/receiver v0.108.1
 	go.opentelemetry.io/collector/service v0.108.1
@@ -68,6 +67,7 @@ require (
 	go.opentelemetry.io/collector/consumer v0.108.1 // indirect
 	go.opentelemetry.io/collector/consumer/consumerprofiles v0.108.1 // indirect
 	go.opentelemetry.io/collector/consumer/consumertest v0.108.1 // indirect
+	go.opentelemetry.io/collector/internal/globalgates v0.108.1 // indirect
 	go.opentelemetry.io/collector/pdata v1.14.1 // indirect
 	go.opentelemetry.io/collector/pdata/pprofile v0.108.1 // indirect
 	go.opentelemetry.io/collector/pdata/testdata v0.108.1 // indirect