files/kubelet: specify "TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256"

To address some handshake errors. Root cause is still pending for
investigation.

Signed-off-by: Gyuho Lee <leegyuho@amazon.com>

files/kubelet-config-with-secret-polling.json

@@ -31,5 +31,5 @@
   "serializeImagePulls": false,
   "serverTLSBootstrap": true,
   "configMapAndSecretChangeDetectionStrategy": "Cache",
-  "tlsCipherSuites": ["TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256"]
+  "tlsCipherSuites": ["TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256"]
 }