fix: normalize req.irql spacing <=APC_LEVEL -> <= APC_LEVEL across 41 files

[cristeigabriela]

Context: This is part of a series of pull requests.

I am working on a sister project to sparse, the sdk-api parser, and in the process, I automated finding issues in windows-driver-docs-ddi (I've also done this for sdk-api.)

I'm now submitting patches for everything I've found for review. All the changes were tested in a branch where all of them are applied, and every single YAML frontmatter parses correctly.

All 12 PRs in this series — merging guide

#	PR	Branch	Files
1	#1660	fix/typos-frontmatter	5
2	#1661	fix/acxmisc-acxobjectbagretrieveblob-irql	1
3	#1662	fix/iddcx-irql-empty	14
4	#1663	fix/silo-and-reparse-irql	8
5	#1664	fix/portcls-na-dll	2
6	#1665	fix/irql-apc-level-spacing	41
7	#1666	fix/irql-passive-abbreviation	2
8	#1667	fix/irql-dispatch-level-spacing	301
9	#1668	fix/ntoskrnl-lib-misfiled-as-dll	3
10	#1669	fix/strip-irql-prose-prefix	80
11	#1670	fix/irql-trailing-period-and-passive-case	133
12	#1671	fix/irql-prose-to-operator	239

All of the 12 PRs have zero pairwise file overlap. They can be merged individually, in any order, and there will not be merge conflicts between them.

After every PR is merged, all 10,915 nf-*.md frontmatter blocks will still parse cleanly as YAML.

A reference branch with all of the PRs merged at once is at integration/all-open-prs.

If you look at the image below, you're going to see that the current req.irql distribution is very weird:

This is currently one of the leading req.irql field values, and it's kind of annoying and inconsistent, considering there's 531 other entries where it is <= APC_LEVEL. This will lead to all these 41 entries being absorbed by that one.

This PR attempts to even it out some.