Strange Partitions which are not mounted

I have a Home license running on a Zotac CI323 with a 32GB SSD. It runs quite well.

However I noticed that the /tmp partition is rather small, only 950MB! I got already in trouble when failing AV updates were filling this up.

So I looked at the partition table:

Disk /dev/sda: 32.0 GB, 32017047552 bytes
255 heads, 63 sectors/track, 3892 cylinders, total 62533296 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x000d008d

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048      718848      358400+  83  Linux
/dev/sda2          718849     9107456     4194304   82  Linux swap / Solaris
/dev/sda3         9107457    11204608     1048576   83  Linux
/dev/sda4        11204609    62533295    25664343+   f  W95 Ext'd (LBA)
/dev/sda5        11204610    27586560     8190975+  83  Linux
/dev/sda6        27586562    38850560     5631999+  83  Linux
/dev/sda7        38850562    60389376    10769407+  83  Linux
/dev/sda8        60389378    62158848      884735+  83  Linux

And then I did this:

gate:/ # mount | grep sda
/dev/sda6 on / type ext4 (rw,noatime,discard)
/dev/sda1 on /boot type ext4 (ro,noatime,discard)
/dev/sda5 on /var/storage type ext4 (rw,noatime,discard)
/dev/sda7 on /var/log type ext4 (rw,noatime,discard)
/dev/sda8 on /tmp type ext4 (rw,noatime,discard)

It seems, sda3 is not mounted.

So I mounted it and it shows this:

total 10168
drwxr-xr-x 5 root root     4096 Feb  9  2016 .
drwxr-xr-x 3 root root     4096 Oct 19 21:34 ..
-rwxr-xr-x 1 root root       47 Feb  9  2016 build
-rwxr-xr-x 1 root root 10311680 Feb  9  2016 install.tar
drwxr-xr-x 2 root root     4096 Feb  9  2016 lists
drwx------ 2 root root    16384 Feb  9  2016 lost+found
drwxr-xr-x 2 root root    61440 Feb  9  2016 rpm

Is this a leftover of the initial installation? Can I delete it safely and resize the other partitions accordingly?