Render valid optimized AMP by default

[ijjk]

This removes the dirty/clean optimizations for AMP only pages since now all optimizations are clean. For AMP only pages you no longer need to use ?amp=1 to access the clean optimized version.

Closes: #7461

[github-actions]

Stats from current PR

Click to expand stats

	zeit/next.js canary	ijjk/next.js upgrade/amp-optimizer	Change
Build Duration	15.7s	15.9s	⚠️ +107ms
node_modules Size	40.9 MB	40.9 MB	⚠️ +25.8 kB
Total Bundle (main, webpack, commons) Size	210 kB	210 kB	✓
Total Bundle (main, webpack, commons) gzip Size	68.9 kB	68.9 kB	✓
Client _app Size	2.92 kB	2.92 kB	✓
Client _app gzip Size	1.2 kB	1.2 kB	✓
Client _error Size	8.25 kB	8.25 kB	✓
Client _error gzip Size	3.13 kB	3.13 kB	✓
Client pages/index Size	288 B	288 B	✓
Client pages/index gzip Size	222 B	222 B	✓
Client pages/link Size	4.76 kB	4.76 kB	✓
Client pages/link gzip Size	2.06 kB	2.06 kB	✓
Client pages/routerDirect Size	411 B	411 B	✓
Client pages/routerDirect gzip Size	296 B	296 B	✓
Client pages/withRouter Size	393 B	393 B	✓
Client pages/withRouter gzip Size	280 B	280 B	✓
Client main Size	23.3 kB	23.3 kB	✓
Client main gzip Size	7.74 kB	7.74 kB	✓
Client commons Size	184 kB	184 kB	✓
Client commons gzip Size	59.7 kB	59.7 kB	✓
Client webpack Size	1.49 kB	1.49 kB	✓
Client webpack gzip Size	769 B	769 B	✓
Base Rendered Size	1.34 kB	1.34 kB	✓
Build Dir Size	813 kB	813 kB	-444 B

Click to expand serverless stats

	zeit/next.js canary	ijjk/next.js upgrade/amp-optimizer	Change
Build Duration	16.6s	16.2s	-346ms
node_modules Size	40.9 MB	40.9 MB	⚠️ +25.8 kB
Total Bundle (main, webpack, commons) Size	210 kB	210 kB	✓
Total Bundle (main, webpack, commons) gzip Size	68.9 kB	68.9 kB	✓
Client _app Size	2.92 kB	2.92 kB	✓
Client _app gzip Size	1.2 kB	1.2 kB	✓
Client _error Size	8.25 kB	8.25 kB	✓
Client _error gzip Size	3.13 kB	3.13 kB	✓
Client pages/index Size	288 B	288 B	✓
Client pages/index gzip Size	222 B	222 B	✓
Client pages/link Size	4.76 kB	4.76 kB	✓
Client pages/link gzip Size	2.06 kB	2.06 kB	✓
Client pages/routerDirect Size	411 B	411 B	✓
Client pages/routerDirect gzip Size	296 B	296 B	✓
Client pages/withRouter Size	393 B	393 B	✓
Client pages/withRouter gzip Size	280 B	280 B	✓
Client main Size	23.3 kB	23.3 kB	✓
Client main gzip Size	7.74 kB	7.74 kB	✓
Client commons Size	184 kB	184 kB	✓
Client commons gzip Size	59.7 kB	59.7 kB	✓
Client webpack Size	1.49 kB	1.49 kB	✓
Client webpack gzip Size	769 B	769 B	✓
Serverless pages/link Size	342 kB	341 kB	-786 B
Serverless pages/link gzip Size	87.6 kB	87.4 kB	-198 B
Serverless pages/index Size	333 kB	332 kB	-786 B
Serverless pages/index gzip Size	85.2 kB	85 kB	-202 B
Serverless pages/_error Size	332 kB	332 kB	-786 B
Serverless pages/_error gzip Size	85 kB	84.8 kB	-208 B
Serverless pages/routerDirect Size	333 kB	332 kB	-786 B
Serverless pages/routerDirect gzip Size	85.2 kB	85 kB	-208 B
Serverless pages/withRouter Size	333 kB	332 kB	-786 B
Serverless pages/withRouter gzip Size	85.2 kB	85 kB	-205 B
Build Dir Size	2.38 MB	2.38 MB	-4.16 kB