[chore][internal/filter/filterconfig] Update comment to match functio…

…nality (open-telemetry#31517)

Context:
open-telemetry#31496 (comment)

I believe strict matching was originally the only supported option for
attributes, and regex was added shortly after. I believe this comment
was missed with the update, so it's out of date. Refer to the referenced
comment above for more context and references.

internal/filter/filterconfig/config.go

@@ -105,8 +105,7 @@ type MatchProperties struct {
 	MetricNames []string `mapstructure:"metric_names"`
 
 	// Attributes specifies the list of attributes to match against.
-	// All of these attributes must match exactly for a match to occur.
-	// Only match_type=strict is allowed if "attributes" are specified.
+	// All of these attributes must match for a match to occur.
 	// This is an optional field.
 	Attributes []Attribute `mapstructure:"attributes"`