Additionally remove the KMSv1 Reserved EC Key in KmsKeyring

In Java:

```
private static final String KEY_ID_CONTEXT_KEY = "kms_cmk_id";
```

```
//= specification/s3-encryption/materials/s3-kms-keyring.md#kms-context
//# The stored encryption context with the two reserved keys removed MUST match the provided encryption context.
materialsEncryptionContextCopy.remove(KEY_ID_CONTEXT_KEY);
materialsEncryptionContextCopy.remove(ENCRYPTION_CONTEXT_ALGORITHM_KEY);
```

https://github.com/aws/amazon-s3-encryption-client-python/pull/143 points out we don't currently do this in Python.

首先定位比较已存储加密上下文与所提供上下文的 Python KMS keyring 代码，然后将其行为与 Java 代码片段及所引用的 KMS 上下文规范进行比较。完成的标准是：在比较之前排除两个保留键，并且相关测试覆盖 KMSv1 情况。

由索引模型根据 Issue 内容生成。