[chore]: enable error-is-as rule from testifylint (#6141)

Testifylint is a linter that provides best practices with the use of
testify.

This PR enables
[error-is-as](https://github.com/Antonboom/testifylint?tab=readme-ov-file#error-is-as)
rule from [testifylint](https://github.com/Antonboom/testifylint)

Signed-off-by: Matthieu MOREL <matthieu.morel35@gmail.com>
Co-authored-by: Robert Pająk <pellared@hotmail.com>

.golangci.yml

@@ -248,7 +248,6 @@ linters-settings:
     enable-all: true
     disable:
       - compares
-      - error-is-as
       - expected-actual
       - float-compare
       - formatter

samplers/probability/consistent/tracestate_test.go

@@ -4,7 +4,6 @@
 package consistent
 
 import (
-	"errors"
 	"strconv"
 	"strings"
 	"testing"
@@ -91,7 +90,7 @@ func TestParseTraceStateUnsampled(t *testing.T) {
 			require.False(t, otts.hasPValue(), "should have no p-value")
 
 			if test.expectErr != nil {
-				require.True(t, errors.Is(err, test.expectErr), "not expecting %v", err)
+				require.ErrorIs(t, err, test.expectErr, "not expecting %v", err)
 			}
 			if test.rval != notset {
 				require.True(t, otts.hasRValue())
@@ -168,7 +167,7 @@ func TestParseTraceStateSampled(t *testing.T) {
 			otts, err := parseOTelTraceState(test.in, true)
 
 			if test.expectErr != nil {
-				require.True(t, errors.Is(err, test.expectErr), "not expecting %v", err)
+				require.ErrorIs(t, err, test.expectErr, "not expecting %v", err)
 			} else {
 				require.NoError(t, err)
 			}
@@ -252,7 +251,7 @@ func TestParseTraceStateExtra(t *testing.T) {
 			otts, err := parseOTelTraceState(test.in, test.sampled)
 
 			if test.expectErr != nil {
-				require.True(t, errors.Is(err, test.expectErr), "not expecting %v", err)
+				require.ErrorIs(t, err, test.expectErr, "not expecting %v", err)
 			} else {
 				require.NoError(t, err)
 			}