[fix](DECIMAL) error DECIMAL cat to BOOLEAN (#44326)

[mrhhsg]

In the past, there were issues with converting double and decimal to boolean.
For example, a double value like 0.13 would first be cast to uint8, resulting in 0.
Then, it would be converted to bool, yielding 0 (incorrect, as the expected result is 1).

Similarly, decimal values were directly cast to uint8, leading to non-0/1 values for bool.
This issue arises because Doris internally uses uint8 to represent boolean.

before

mysql> select cast(40.123 as BOOLEAN);
+-------------------------+
| cast(40.123 as BOOLEAN) |
+-------------------------+
|                      40 |
+-------------------------+

now

mysql> select cast(40.123 as BOOLEAN);
+-------------------------+
| cast(40.123 as BOOLEAN) |
+-------------------------+
|                       1 |
+-------------------------+

What problem does this PR solve?

pick #44326
Related PR: #44326

Problem Summary:

Release note

None

Check List (For Author)

• Test

  • Regression test
  • Unit Test
  • Manual test (add detailed scripts or steps below)
  • No need to test or manual test. Explain why:
    • This is a refactor/code format and no logic has been changed.
    • Previous test can cover this change.
    • No code files have been changed.
    • Other reason

• Behavior changed:

  • No.
  • Yes.

• Does this need documentation?

  • No.
  • Yes.

Check List (For Reviewer who merge this PR)

• Confirm the release note
• Confirm test cases
• Confirm document
• Add branch pick label

[Thearas]

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[mrhhsg]

run buildall

[doris-robot]

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