fix(http): make HTTP text import for WAL tables to write via WAL

[ideoma]

REST imp endpoint was not updated to write to WAL tables using WAL infrastructure. This PR makes the writing to behave as expected. Also fixes #3632

[ideoma]

[PR Coverage check]

😍 pass : 70 / 73 (95.89%)

file detail

	path	covered line	new line	coverage
🔵	io/questdb/cairo/TableUtils.java	11	14	78.57%
🔵	io/questdb/cairo/TableReaderMetadata.java	1	1	100.00%
🔵	io/questdb/cutlass/text/CairoTextWriter.java	24	24	100.00%
🔵	io/questdb/cairo/pool/MetadataPool.java	17	17	100.00%
🔵	io/questdb/cairo/DynamicTableReaderMetadata.java	17	17	100.00%

[puzpuzpuz]

Looks like as a side effect of this change, the serial mode of SQL COPY also started writing to WAL. Probably, it's worth it to add some tests around it.

As for the parallel mode where we require the table to be empty, we should at least document that it writes to the end table instead of WAL and/or create a separate GH issue.

WDYT?

[puzpuzpuz]

Looks like as a side effect of this change, the serial mode of SQL COPY also started writing to WAL. Probably, it's worth it to add some tests around it.

Hmm, I forgot that it's used for non-partitioned tables, so it's not applicable to WAL tables. On WAL tables COPY should be parallel always.