FELIX-6812 Follow-up: escape the pid in the service.pid filter (#563)

* FELIX-6812 Follow-up: escape the pid in the service.pid filter

FELIX-6812 replaced getConfiguration(pid, "?") with a listConfigurations call,
and it builds the filter by concatenating the pid. A pid is not a filter-safe
value, and the class already escapes one in findExistingConfiguration.

A pid holding an asterisk builds a substring filter. listConfigurations then
returns configurations the event was not about, and ConfigInstaller writes the
first of them back to that other configuration's file. A pid holding a
parenthesis throws InvalidSyntaxException instead, which the catch reports as a
failure to save, so the configuration is never written back.

escapeFilterValue left the backslash alone, although the OSGi filter grammar
reserves it. A pid holding a backslash therefore stayed ambiguous after the
escaping. The backslash is escaped first, or the escapes added after it would be
escaped a second time.

The method now matches literals rather than patterns. It compiled four patterns
per call, and FELIX-6812 moved it from findExistingConfiguration, called once per
file install, to doConfigurationEvent, called for every configuration event.

Two tests raise CM_UPDATED for a pid holding an asterisk and for a pid holding a
backslash, and each one fails when its escape is removed.

* FELIX-6812 Follow-up: the two tests the change left green and empty

FELIX-6812 moved the CM_UPDATED path from getConfiguration to listConfigurations,
and two tests kept the expectations of the older call. Neither test calls
EasyMock.verify, so an expectation nothing consumes fails nothing.

testUseExistingConfigAndObserveCMDeleted expects listConfigurations for any
argument and answers null. The handler then returns before it reads anything, so
the test asserts nothing at all while it passes. It now expects the filter the
handler builds and answers with a configuration.

testUseExistingConfigWithFileinstallFilenameAndObserveCMDeleted still expects
getConfiguration and update. The CM_UPDATED path writes the file and calls no
method on the configuration, and getConfiguration is reachable from setConfig
only, which this test never calls.

Both tests verify their mocks now, which is what makes an expectation
load-bearing. The dead expectations go, and the Capture that fed update goes
with them. Adding the verify call before removing the expectations fails on
Configuration.update, which is the measurement behind this commit.