test: use gemini-embedding-001 for Gemini Embeddings test (envoyproxy#1246)

**Description**

`gemini-embedding-exp-03-07` is being deprecated by Google.

---------

Signed-off-by: Takeshi Yoneda <[email protected]>

Author: mathetake

tests/extproc/envoy.yaml

@@ -103,7 +103,7 @@ static_resources:
                             headers:
                               - name: x-model-name
                                 string_match:
-                                  exact: gemini-embedding-exp-03-07
+                                  exact: gemini-embedding-001
                           route:
                             auto_host_rewrite: true
                             cluster: gemini

tests/extproc/real_providers_test.go

@@ -111,7 +111,7 @@ func TestWithRealProviders(t *testing.T) {
 		t.Run("embeddings", func(t *testing.T) {
 			for _, tc := range []realProvidersTestCase{
 				{name: "openai", modelName: "text-embedding-3-small", required: internaltesting.RequiredCredentialOpenAI},
-				{name: "gemini", modelName: "gemini-embedding-exp-03-07", required: internaltesting.RequiredCredentialGemini},
+				{name: "gemini", modelName: "gemini-embedding-001", required: internaltesting.RequiredCredentialGemini},
 				{name: "sambanova", modelName: "E5-Mistral-7B-Instruct", required: internaltesting.RequiredCredentialSambaNova},
 				{name: "deepinfra", modelName: "BAAI/bge-base-en-v1.5", required: internaltesting.RequiredCredentialDeepInfra},
 			} {