[fix](build) Fix insecure Python dependency pins in doris-compose, dbt-doris, and cost_model (#64928)

### What problem does this PR solve?

Issue Number: N/A

Related PR: #63188

Problem Summary:
Three Python requirements files have dependency pins that allow
installing versions with known security issues.

**docker/runtime/doris-compose/requirements.txt**

The `requests<=2.31.0` constraint sets an upper bound but no lower
bound, so pip can resolve to any version below 2.31.0. Versions before
2.31.0 are affected by CVE-2023-32681 (Proxy-Authorization header leaked
on cross-domain redirects). Changed to `requests>=2.31.0` to set a
secure floor.

**extension/dbt-doris/dev-requirements.txt**

The `mysql-connector-python>=8.0.0,<8.3` lower bound allows versions
with known authentication bypass issues. Raised the lower bound to
`>=8.0.33` which includes the relevant fixes.

**tools/cost_model_evaluate/requirements.txt**

The `mysql_connector_repackaged==0.3.1` package is an unofficial
third-party repackage of the MySQL connector whose last PyPI release was
in 2014. Replaced with the official `mysql-connector-python>=8.0.33,<9`
package. The code in `sql_executor.py` imports `mysql.connector` which
both packages provide, so this is a drop-in replacement.

docker/runtime/doris-compose/requirements.txt

@@ -22,7 +22,7 @@ jsonpickle
 prettytable
 pymysql
 python-dateutil
-requests<=2.31.0
+requests>=2.31.0
 
 # NOTICE: if install docker failed, specific pyyaml version and docker version
 #pyyaml==5.3.1

extension/dbt-doris/dev-requirements.txt

@@ -37,4 +37,4 @@ pytz
 tox>=3.13
 twine
 wheel
-mysql-connector-python>=8.0.0,<8.3
+mysql-connector-python>=8.0.33,<8.3

tools/cost_model_evaluate/requirements.txt

@@ -16,4 +16,4 @@
 # under the License.
 
 matplotlib==3.7.0
-mysql_connector_repackaged==0.3.1
+mysql-connector-python>=8.0.33,<9