feat: remove support for FLOAT/DOUBLE type partition field

[lszskye]

Purpose

remove support for FLOAT/DOUBLE type partition field

[lucasfang]

+1

[zjw1111]

Requesting changes for one scope issue:

• src/paimon/testing/utils/data_generator.cpp: removing FLOAT / DOUBLE support from DataGenerator::WriteBinaryRow also affects bucket-row construction, not only partition-row construction. SplitArrayByPartitionAndBucket() uses the same ExtractPartialRow(binary_row, bucket_fields) path to build bucket_row for bucket id calculation. The schema validation added in this PR only rejects FLOAT / DOUBLE partition keys, while FLOAT / DOUBLE bucket keys are still allowed and the production BucketIdCalculator::WriteBucketRow still supports them. As a result, a legal table with a FLOAT / DOUBLE bucket key that is not a partition key can become unsupported in the test data generation path. Please keep the FLOAT / DOUBLE branches in DataGenerator::WriteBinaryRow, or split the helper so the new restriction applies only to the partition converter / schema validation path.