feat(experimentalIdentityAndAuth): remove generic @aws.auth#sigv4 support

This support will now live in `smithy-aws-typescript-codegen`.

Author: Steven Yuan

smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/auth/http/integration/AddSigV4AuthPlugin.java

@@ -8,7 +8,6 @@ software.amazon.smithy.typescript.codegen.auth.http.integration.HttpAuthRuntimeE
 software.amazon.smithy.typescript.codegen.auth.http.integration.AddNoAuthPlugin
 software.amazon.smithy.typescript.codegen.auth.http.integration.AddHttpApiKeyAuthPlugin
 software.amazon.smithy.typescript.codegen.auth.http.integration.AddHttpBearerAuthPlugin
-software.amazon.smithy.typescript.codegen.auth.http.integration.AddSigV4AuthPlugin
 software.amazon.smithy.typescript.codegen.integration.AddHttpApiKeyAuthPlugin
 software.amazon.smithy.typescript.codegen.integration.AddBaseServiceExceptionClass
 software.amazon.smithy.typescript.codegen.integration.AddSdkStreamMixinDependency