`WITH max parallel create index 1` is still parallelly run many `CREATE INDEX` and the importing of next table

[x] pgloader --version

pgloader version "3.6.af8c3c1"
compiled with SBCL 2.1.11.debian

[x] did you test a fresh compile from the source tree?
[x] did you search for other similar issues?

[x] how can I reproduce the bug?

LOAD DATABASE
     FROM mysql://user:@localhost/tbm
     INTO pgsql://user:@localhost/tbm

WITH quote identifiers, max parallel create index 1
;

[x] pgloader output you obtain

2024-04-12T22:17:18.008001+08:00 LOG pgloader version "3.6.af8c3c1"                                                     
2024-04-12T22:17:18.092001+08:00 LOG Migrating from #<MYSQL-CONNECTION mysql://user@localhost:3306/tbm {1007F8F823}>
2024-04-12T22:17:18.092001+08:00 LOG Migrating into #<PGSQL-CONNECTION pgsql://user@localhost:5432/tbm {1007F90443}>
2024-04-12T22:17:21.728043+08:00 LOG report summary reset

By periodically running

SELECT * FROM pg_stat_activity WHERE application_name = 'pgloader';

I can see when the COPY for first table is complete there will be multiple(as many as the count of indexes on that table) of CREATE TABLE running and the COPY of next table, this behavior will slow down database and all these queries. Then I tried decreasing the parallelism by max parallel create index 1 https://pgloader.readthedocs.io/en/latest/batches.html

By default, as many CREATE INDEX threads as the maximum number of indexes per table are found in your source schema. It is possible to set the max parallel create index WITH option to another number in case there’s just too many of them to create.

but it's still the same.

dimitri / pgloader

`WITH max parallel create index 1` is still parallelly run many `CREATE INDEX` and the importing of next table #1576