padtemplate: Directly unreference the documentation caps

The public-facing API has a (valid) protection against NULL caps. We can just
directly remove it.

Part-of: <!515>
29 jobs for master in 28 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Preparation
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manual #2982684
manual
manifest
 
  Build
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gstreamer
build cerbero cross-android universal
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gst-ios-13.2
build cerbero cross-ios universal
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build cerbero cross win32
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build cerbero cross win64
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gstreamer
build cerbero fedora x86_64
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gst-macos-10.15
build cerbero macos x86_64
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build clang fedora x86_64
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1809 windows docker allowed to fail manual
build msys2
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build nodebug fedora x86_64
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build static fedora x86_64
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build static nodebug fedora x86_64
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1809 windows docker
build vs2017 amd64
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1809 windows docker
build vs2017 x86
 
  Test
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check fedora
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valgrind bad
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valgrind base
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valgrind core
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valgrind ges
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valgrind good
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  Integrate
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cross-android universal examples
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gst-ios-13.2
cross-ios universal examples
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documentation