Add new 8-core Macs to try server.
Add new 8-core Macs to try server.

We'll monitor the cycle times on these bots to figure out how many of them we need to replace the 4-core ones.

BUG=313077

Review URL: https://codereview.chromium.org/458413002

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@288823 0039d316-1c4b-4281-b951-d872f2087c98

eunchong/build,eunchong/build,eunchong/build,eunchong/build