BUG: to_sql with sqlalchemy[mysql], if_exists='repalce' raise 'sqlalchemy.exc.NoSuchTableError'; if_exists='fail' raise 'Table already exists'
### 

- [X] I have checked that this issue has not already been reported.

- [X] I have confirmed this bug exists on the [latest version](https://pandas.pydata.org/docs/whatsnew/index.html) of pandas.

- [ ] I have confirmed this bug exists on the master branch of pandas.


### Reproducible Example

```python
class Database:
    def __init__(self):
        self.save_schema = 'build_dwd'
        self.save_table = 'dwd_abtest_report'
        self.mysql_dwd_config = {
            'drivername': 'mysql+pymysql',
            'username': 'xxx',
            'password': 'xxx@#$xx',
            'host': 'am-xxx.ads.aliyuncs.com',
            'port': xxx,
        }
        self.mysql_engine_url = sqlalchemy.engine.URL.create(**self.mysql_dwd_config)
        self.mysql_dwd_engine = sqlalchemy.create_engine(self.mysql_engine_url)



    def get_mysql_data(self, sql):
        return pandas.read_sql(sql=sql, con=self.mysql_dwd_engine, chunksize=None)

    def write_mysql_data(self, df, if_replace=False):
        df.to_sql(
            con=self.mysql_dwd_engine,
            schema=self.save_schema,
            name=self.save_table,
            if_exists='replace' if if_replace else 'append',
            index=False,
            index_label='id',
            chunksize=10000,
        )
```


### Issue Description

BUG: to_sql with sqlalchemy[mysql],
if_exists='repalce' raise 'sqlalchemy.exc.NoSuchTableError'; 
if_exists='fail' raise 'Table already exists'.

In fact, `if_exists='repalce' ` has error.  when I gave schema, but it unknow schema.

### Expected Behavior

if_exists='repalce' should drop table, create table, and insert data.

### Installed Versions

<details>

INSTALLED VERSIONS
------------------
commit           : 5f648bf1706dd75a9ca0d29f26eadfbb595fe52b
python           : 3.8.5.final.0
python-bits      : 64
OS               : Darwin
OS-release       : 19.6.0
Version          : Darwin Kernel Version 19.6.0: Mon Aug 31 22:12:52 PDT 2020; root:xnu-6153.141.2~1/RELEASE_X86_64
machine          : x86_64
processor        : i386
byteorder        : little
LC_ALL           : None
LANG             : None
LOCALE           : zh_CN.UTF-8
pandas           : 1.3.2
numpy            : 1.20.3
pytz             : 2020.1
dateutil         : 2.8.1
pip              : 21.2.4
setuptools       : 50.3.1.post20201107
Cython           : 0.29.21
pytest           : 6.1.1
hypothesis       : None
sphinx           : 4.1.2
blosc            : None
feather          : None
xlsxwriter       : 1.3.7
lxml.etree       : 4.6.3
html5lib         : 1.1
pymysql          : 1.0.2
psycopg2         : None
jinja2           : 2.11.3
IPython          : 7.28.0
pandas_datareader: None
bs4              : 4.9.3
bottleneck       : 1.3.2
fsspec           : 2021.05.0
fastparquet      : None
gcsfs            : None
matplotlib       : 3.4.3
numexpr          : 2.7.1
odfpy            : None
openpyxl         : 3.0.5
pandas_gbq       : None
pyarrow          : 5.0.0
pyxlsb           : None
s3fs             : None
scipy            : 1.7.1
sqlalchemy       : 1.4.23
tables           : 3.6.1
tabulate         : None
xarray           : None
xlrd             : 1.2.0
xlwt             : 1.3.0
numba            : 0.54.0

</details>
