GH-49502: [Parquet][C++] Fix missing overflow check for dictionary encoder indices count

[aryansri05]

Closes #49502
Rationale for this change

When writing large dictionary-encoded Parquet data with
ARROW_LARGE_MEMORY_TESTS=ON, two tests were failing:

• TestColumnWriter.WriteLargeDictEncodedPage — expected 2 pages, got 7501
• TestColumnWriter.ThrowsOnDictIndicesTooLarge — expected ParquetException,
  got nothing thrown

The root cause is that PutIndicesTyped() in DictEncoderImpl had no check
for when the total number of buffered dictionary indices exceeds INT32_MAX.
The existing overflow check in FlushValues() only checks the buffer size in
bytes, not the index count, so it never triggered for this case.

What changes are included in this PR?

Added an overflow check in DictEncoderImpl::PutIndicesTyped() immediately
after buffered_indices_.resize():

if (buffered_indices_.size() >
static_cast<size_t>(std::numeric_limits<int32_t>::max())) {
throw ParquetException("Total dictionary indices count (",
buffered_indices_.size(),
") exceeds maximum int value");
}

This makes the encoder throw a ParquetException with a message containing
"exceeds maximum int value" when the index count overflows, which is exactly
what ThrowsOnDictIndicesTooLarge expects.

Are these changes tested?

Yes — the existing tests in column_writer_test.cc cover this fix:

• TestColumnWriter.ThrowsOnDictIndicesTooLarge
• TestColumnWriter.WriteLargeDictEncodedPage

Both tests were failing before this fix and should pass after.
Tests require building with ARROW_LARGE_MEMORY_TESTS=ON.

This PR contains a "Critical Fix"— previously, writing dictionary-encoded
data with more than INT32_MAX indices would silently produce incorrect output
(wrong page count) instead of raising an error. This fix makes the encoder
correctly throw a ParquetException in that scenario.

• GitHub Issue: [C++][Parquet] parquet-writer-test Large memory tests fail on TestColumnWriter.WriteLargeDictEncodedPage and TestColumnWriter.ThrowsOnDictIndicesTooLarge #49502

[github-actions]

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[github-actions]

⚠️ GitHub issue #49502 has been automatically assigned in GitHub to PR creator.

[raulcd]

I don't think this is what we are looking for here. This will still fail the WriteLargeDictEncodedPage test which is one of the two tests that was supposed to be fixed by this PR. I've pushed a commit to my PR to add Large memory tests to CI with a fix. Basically the tests where done before having max_rows_per_page and we are expecting those tests to have huge data pages. See the commit here:
ab1c5ad
I am currently validating whether the tests are passing with my fix.

[aryansri05]

Thank you for the explanation! I can see now that
WriteLargeDictEncodedPage needs the test updated
with .max_rows_per_page(INT64_MAX) to account for
the new page size behavior, while my overflow check
fixes ThrowsOnDictIndicesTooLarge.

Should I update my PR to include both fixes together,
or would you prefer to handle them separately?