Fix history displays irrelevant changes

[thachlp]

Motivate: The history of a directory includes changes in directories share the name. For instance: the history of /foo displays changes for /foo2, /foo3, /foobar ...

Modifications: Add a slash (/) before ** in the path (path + "/**"). The pattern foo/** matches /foo/anything, /foo/subdir/file, but it does not match anything that isn't a subpath of /foo.

Result Fixes https://github.com/line/centraldogma/issues/902