`select into` may fail if `HADOOP_CONF_DIR` or `YARN_CONF_DIR` env are accidentally configured

**Bug Description**
`select into outfile '/tmp/out.csv'` may fail if the `HADOOP_CONF_DIR` or `YARN_CONF_DIR` environmental variables are accidentally configured and its `defaultfs` is `hdfs`.

**Expected Behavior**
For `outfile '/tmp/out.csv'`, users expect to write into local filesystems.
Possible solutions may be:
- add Q&A to show the potential issue
- guide users to specify 'file:///tmp/out.csv' to avoid the confusion

**Steps to Reproduce**

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Look at the code that handles 'select into outfile' parsing and path resolution, likely in the SQL engine or filesystem abstraction layer. Check how environment variables like HADOOP_CONF_DIR and YARN_CONF_DIR are read and how they affect the default filesystem. The fix may involve ensuring local file paths are not misinterpreted as HDFS, or improving error messages. Test by setting these environment variables and running a simple select into outfile command.

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