[FixRM #8319] - Properly disable BLANK_PASSWORDS for ektron_cms400net

In module ektron_cms400net.rb, datastore option "BLANK_PASSWORDS" is
set to false by default, because according to the original author, a
blank password will result in account lockouts. Since the user should
never set "BLANK_PASSWORDS" to true, this option should never be
presented as an option (when issuing the "show options").

While fixing #8319, I also noticed another bug at line 108, where
res.code is used when res could be nil due to a timeout, so I ended
up fixing it, too.
Validate datastore option "YEAR"

The YEAR option is a numeric value, so should be OptInt in order to
go through validation.

[FixRM #8345]
[FixRM #8344]
Fix SessionManager database leak

All database access should be wrapped in with_connection blocks.

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[Story #55586616]
Fix a few database leaks

All database access should be wrapped in with_connection blocks.

To avoid breaking git blame with a bunch of whitespace, I outdented
the with_connection blocks as seems to be common in db.rb.

[Story #55586616]
Type conversion
Better fixes
Land #2266, @wchen-r7's patch forn [SeeRM #8345] and [SeeRM #8344]
Land #2259, @wchen-r7's patch for [SeeRM #8319]
Merge pull request #2271 from bturner-r7/bug/db-leaks

Land #2271, Fix database connection leaks