Fix building HTML fixtures during integration tests (#32886)
Fix building HTML fixtures during integration tests (#32886)

The `buildRuntime` (which is run unless you specify `--nobuild` flag) does a full build system cleaning, which also wipes out the built `test-bin` directory. We need to compile the HTML fixtures _after_ it, so they're not immediately cleaned.
Gregable/amphtml,sharethrough/amphtml,jpettitt/amphtml,smartadserver/amphtml,sharethrough/amphtml,ampproject/amphtml,jpettitt/amphtml,danielrozenberg/amphtml,jpettitt/amphtml,alanorozco/amphtml,honeybadgerdontcare/amphtml,honeybadgerdontcare/amphtml,nexxtv/amphtml,Gregable/amphtml,voyagegroup/amphtml,jridgewell/amphtml,lannka/amphtml,rsimha-amp/amphtml,voyagegroup/amphtml,prateekbh/amphtml,rsimha-amp/amphtml,danielrozenberg/amphtml,lannka/amphtml,media-net/amphtml,jridgewell/amphtml,mhc-gh/amphtml,nexxtv/amphtml,honeybadgerdontcare/amphtml,lannka/amphtml,jridgewell/amphtml,jpettitt/amphtml,smartadserver/amphtml,ampproject/amphtml,sharethrough/amphtml,lannka/amphtml,mhc-gh/amphtml,alanorozco/amphtml,danielrozenberg/amphtml,media-net/amphtml,Gregable/amphtml,honeybadgerdontcare/amphtml,media-net/amphtml,voyagegroup/amphtml,jridgewell/amphtml,nexxtv/amphtml,rsimha-amp/amphtml,alanorozco/amphtml,smartadserver/amphtml,voyagegroup/amphtml,ampproject/amphtml,honeybadgerdontcare/amphtml,prateekbh/amphtml,alanorozco/amphtml,ampproject/amphtml,Gregable/amphtml,mhc-gh/amphtml,danielrozenberg/amphtml,prateekbh/amphtml,ampproject/amphtml,alanorozco/amphtml,jridgewell/amphtml,smartadserver/amphtml,mhc-gh/amphtml,lannka/amphtml,Gregable/amphtml,mhc-gh/amphtml,Gregable/amphtml,jridgewell/amphtml,voyagegroup/amphtml,prateekbh/amphtml,jpettitt/amphtml,rsimha-amp/amphtml,alanorozco/amphtml,mhc-gh/amphtml,honeybadgerdontcare/amphtml,sharethrough/amphtml,prateekbh/amphtml,media-net/amphtml,media-net/amphtml,media-net/amphtml,danielrozenberg/amphtml,mhc-gh/amphtml,sharethrough/amphtml,alanorozco/amphtml,lannka/amphtml,Gregable/amphtml,voyagegroup/amphtml,jpettitt/amphtml,danielrozenberg/amphtml,ampproject/amphtml,alanorozco/amphtml,voyagegroup/amphtml,rsimha-amp/amphtml,jpettitt/amphtml,mhc-gh/amphtml,rsimha-amp/amphtml,media-net/amphtml,honeybadgerdontcare/amphtml,jridgewell/amphtml,ampproject/amphtml,prateekbh/amphtml,jpettitt/amphtml,nexxtv/amphtml,prateekbh/amphtml,danielrozenberg/amphtml,sharethrough/amphtml,lannka/amphtml,rsimha-amp/amphtml,Gregable/amphtml,nexxtv/amphtml,nexxtv/amphtml,danielrozenberg/amphtml,ampproject/amphtml,media-net/amphtml,smartadserver/amphtml,smartadserver/amphtml,nexxtv/amphtml