Apporach 2: Remove redundant creation of Vector while reading line (T…

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In the 'read_line' function, we split the line at ';' and then collect
the split data into a vector. This collection is redundant because we
discard this vector at the end of function.

The 'collect()' call has to make a system call to allocate some memory
on heap, and since we do this for 1 billion lines - the extra overhead
time for creating space for vector accumulates.

Instead of using 'collect()' we only split the line and use the
interators to extract the values. This removes the necessity of talking
to the OS.