[pkg/stanza] Update KeyValue parser to use parseutils pkg (#31291)

**Description:** <Describe what has changed.>

Updates the KeyValue parser to use the parseutils pkg and subsequent
functions

**Link to tracking Issue:** N/A

Follows up on this
[comment](#31035 (comment))
about merging functionality between Stanza and OTTL key value parsing

**Testing:** 

Unit tests still pass, had to update one because of different wording in
err message

**Documentation:** N/A

pkg/stanza/operator/parser/keyvalue/keyvalue.go

@@ -7,11 +7,10 @@ import (
 	"context"
 	"errors"
 	"fmt"
-	"strings"
 
-	"go.uber.org/multierr"
 	"go.uber.org/zap"
 
+	"github.com/open-telemetry/opentelemetry-collector-contrib/internal/coreinternal/parseutils"
 	"github.com/open-telemetry/opentelemetry-collector-contrib/pkg/stanza/entry"
 	"github.com/open-telemetry/opentelemetry-collector-contrib/pkg/stanza/operator"
 	"github.com/open-telemetry/opentelemetry-collector-contrib/pkg/stanza/operator/helper"
@@ -98,67 +97,10 @@ func (kv *Parser) parser(input string, delimiter string, pairDelimiter string) (
 		return nil, fmt.Errorf("parse from field %s is empty", kv.ParseFrom.String())
 	}
 
-	pairs, err := splitPairs(input, pairDelimiter)
+	pairs, err := parseutils.SplitString(input, pairDelimiter)
 	if err != nil {
 		return nil, fmt.Errorf("failed to parse pairs from input: %w", err)
 	}
 
-	parsed := make(map[string]any)
-
-	for _, raw := range pairs {
-		m := strings.SplitN(raw, delimiter, 2)
-		if len(m) != 2 {
-			e := fmt.Errorf("expected '%s' to split by '%s' into two items, got %d", raw, delimiter, len(m))
-			err = multierr.Append(err, e)
-			continue
-		}
-
-		key := strings.TrimSpace(m[0])
-		value := strings.TrimSpace(m[1])
-
-		parsed[key] = value
-	}
-
-	return parsed, err
-}
-
-// splitPairs will split the input on the pairDelimiter and return the resulting slice.
-// `strings.Split` is not used because it does not respect quotes and will split if the delimiter appears in a quoted value
-func splitPairs(input, pairDelimiter string) ([]string, error) {
-	var result []string
-	currentPair := ""
-	delimiterLength := len(pairDelimiter)
-	quoteChar := "" // "" means we are not in quotes
-
-	for i := 0; i < len(input); i++ {
-		if quoteChar == "" && i+delimiterLength <= len(input) && input[i:i+delimiterLength] == pairDelimiter { // delimiter
-			if currentPair == "" { // leading || trailing delimiter; ignore
-				continue
-			}
-			result = append(result, currentPair)
-			currentPair = ""
-			i += delimiterLength - 1
-			continue
-		}
-
-		if quoteChar == "" && (input[i] == '"' || input[i] == '\'') { // start of quote
-			quoteChar = string(input[i])
-			continue
-		}
-		if string(input[i]) == quoteChar { // end of quote
-			quoteChar = ""
-			continue
-		}
-
-		currentPair += string(input[i])
-	}
-
-	if quoteChar != "" { // check for closed quotes
-		return nil, fmt.Errorf("never reached end of a quoted value")
-	}
-	if currentPair != "" { // avoid adding empty value bc of a trailing delimiter
-		return append(result, currentPair), nil
-	}
-
-	return result, nil
+	return parseutils.ParseKeyValuePairs(pairs, delimiter)
 }

pkg/stanza/operator/parser/keyvalue/keyvalue_test.go

@@ -147,7 +147,7 @@ func TestParserStringFailure(t *testing.T) {
 	parser := newTestParser(t)
 	_, err := parser.parse("invalid")
 	require.Error(t, err)
-	require.Contains(t, err.Error(), fmt.Sprintf("expected '%s' to split by '%s' into two items, got", "invalid", parser.delimiter))
+	require.Contains(t, err.Error(), fmt.Sprintf("cannot split %q into 2 items, got 1 item(s)", "invalid"))
 }
 
 func TestParserInvalidType(t *testing.T) {